From
Flowcharts
to
Python
Activity
Workbook
LLiissaa M
M.. O
Olliivviieerrii,, S
SS
SJJ,, P
PhhD
D
From Flowcharts to Python
This Activity Workbook introduces students who already know flowchart fundamentals to the
Python Programming language.
The materials in this booklet were developed to help students collaborate with each other in the
learning process and to become self-learners in an active learning environment. Students learn
programming concepts by doing programming and reflecting on the results of the activities that they
engage in.
Author: Lisa M. Olivieri, SSJ, Ph.D.
2
Name: _______________________________________
Partners:
________________________________
Python Activity 1: Flowcharts and Python
“What is the relationship between a flowchart and a Python program?”
Learning Objectives
Students will be able to:
Content:
Explain how to display data in Python
Explain how to create a comment in Python
Determine the difference between a string literal and a number
Process:
Create print statements in Python
Create Python code that displays results to calculated addition facts
Discuss problems and programs with all group members
Prior Knowledge
Understanding of flowchart output symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 1
Critical Thinking Questions:
Python Program
Flowchart
1. What does the line of Python code in the Python program do?
_________________________________________________________________________________
_________________________________________________________________________________
2. Circle equivalent representation of the Python code in the flowchart.
3. Execute following code. What output is produced?
a. print(“Hello, my name is Pat!”) ________________________________
b. print(Hello, my name is Pat)
________________________________
c. print(“Hello.\nMy name is Pat”)
________________________________
Python Activity 1: Flowcharts and Python
4.
Was there a problem with any of the sample code in question 3? If so, what caused the problem?
______________________________________________________________________________
______________________________________________________________________________
5.
What caused the different output format for samples “a” and “c” in question 3?
______________________________________________________________________________
______________________________________________________________________________
6.
What do you think the following Python statements output?
a. print(2+5)
_________________________
b. print(2*5)
_________________________
c. print(“2+5”)
_________________________
d. print(“Age:”,20)
_________________________
Enter the statements in the Python interpreter to verify your answers.
7.
Examine the output
for each statement in question 6.
a. What is the difference in the output for the statements in “a” and “c” of question 6?
______________________________________________________________________________
b. What caused the difference? ____________________________________________________
______________________________________________________________________________
c. Which statements contain a string literal?
______________________________________________________________________________
______________________________________________________________________________
d. What does the comma (,) do in the print statement in part “d” of question 6? How does it
affect the spacing of the output?
______________________________________________________________________________
______________________________________________________________________________
8.
Examine the following code and its output. What do the first three lines of the program do?
Output
______________________________________________________________________________
______________________________________________________________________________
4
Python Activity 1: Flowcharts and Python
9. What would happen if you placed a “#” in front of the code:
in the
previous program?
______________________________________________________________________________
______________________________________________________________________________
Application Questions: Use the Python interpreter to design and check your work
1. Create a Python program containing three statements to implement the flowchart on the first page
of this activity. Write the statements below.
2. Create one Python statement to produce the output expected from the flowchart. Be sure the
output is printed on three lines.
3. Create a Python program containing two statements that prints the output
to the right. Have the program calculate the answers to the two
arithmetic problems.
5
Python Activity 1: Flowcharts and Python
Notes and Questions
Make note of any questions you have about Activity 1 on this page.
6
Name: _______________________________________
Partners:
________________________________
Python Activity 2: Input and Variables in Python
“How do you input and store data in a Python program?”
Learning Objectives
Students will be able to:
Content:
Explain how to input data in Python
Explain the meaning and purpose of a variable
Determine if a variable name is valid
Explain concatenation and the use of “+”
Process:
Create input statements in Python
Create Python code that prompts the user for data and stores it in a variable
Create valid and good variable names
Prior Knowledge
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 2
Critical Thinking Questions:
Python Program
Flowchart Program
1. Enter and execute the Python program. What is printed on the screen when the Python program is
executed?
_________________________________________________________________________________
_________________________________________________________________________________
FYI: input() and print() are functions in Python.
2. Draw a line between each flowchart symbol and its corresponding Python code.
Python Activity 2: Input and Variables in Python
3. Examine the first line of Python program: name = input(“What is your name? ”)
a. What happens when this line of code is executed?
______________________________________________________________________________
b. What appears on the screen when this line of code is executed?
______________________________________________________________________________
FYI: The words that appear on the screen to tell the user what to enter are known as a prompt.
c.
What happens to the data when the user enters their name and presses the Enter button? That is,
where is their name stored?
______________________________________________________________________________
FYI: The word name in the Python code is a variable –
name given to a memory location used to store data.
4. What happens when you execute each of the following lines of Python code?
a. name? = input(“What is your name?”)
______________________________________________________________________________
______________________________________________________________________________
b. your name = input(“What is your name?”)
______________________________________________________________________________
______________________________________________________________________________
c. 1st_name = input(“What is your name?”)
______________________________________________________________________________
______________________________________________________________________________
d. from = input(“Where were you born?”)
______________________________________________________________________________
______________________________________________________________________________
5. Examine the errors that occurred when executing the lines of code in question 5. Then examine the
following lines of valid code.
name2 = input(“What is your name?”)
your_name = input(“What is your name?”)
yourName = input(“What is your name?”)
List the rules that need to be followed to create a valid variable name.
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
8
Python Activity 2: Input and Variables in Python
6. Are the following variable names valid? Are they good names? Why or why not?
Variable name
price
costoffirstitem
Ic
firstName
7.
Comments about variable name
Execute the following lines of code. Is the output what you would expect? Why or why not?
_________________________________________________________________________________
_________________________________________________________________________________
8. Use the following set of Python statements to answer the questions below.
a. State the output for each of line of code.
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
b. Examine the first two print statements. How are they different? Does the difference affect the
output?
_________________________________________________________________________________
_________________________________________________________________________________
c. Notice that some statements include a comma (,) between the two literals being printed and some
statements use a “+”. Do they produce the same output? ____________________
d. Explain the purpose of the comma.
_________________________________________________________________________________
_________________________________________________________________________________
e. Why does the last print statement crash the program? What would you do to correct it?
_________________________________________________________________________________
_________________________________________________________________________________
FYI: “+” concatenates two strings. The strings can be string literals or a variable containing string literals.
9
Python Activity 2: Input and Variables in Python
9. State what is displayed on the screen when the following program is executed:
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
Application Questions: Use the Python Interpreter to input your code and check your work
1. State a good variable name for an employee’s ID number.
________________________________
2. Write a line of Python code that prompts the user for the name of their favorite ice cream and stores it
in a valid variable name.
__________________________________________________________
3. Crazy Sentence Program. Create a program that prompts the user for the name of an animal, a color,
the name of a vehicle, and the name of a city. Then print a sentence that contains the user input in the
following order. Include the additional words in the sample output as part of your output. Example:
Assume the user enters the words: tiger, green, motorcycle, and Wildwood. The output would be:
The green tiger drove the motorcycle to Wildwood.
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
Notes and Questions
Make note of any questions you have about Activity 2 on this page.
10
Python Activity 3 Part A: Arithmetic Operations and Assignment Statements
Name: _______________________________________
Partners:
________________________________
Python Activity 3 Part A: Arithmetic Operations and Assignment Statements
“Get the program to compute that!”
“How do I assignment values to variables?”
Learning Objectives
Students will be able to:
Content:
Explain each Python arithmetic operator
Explain the meaning and use of an assignment statement
Review string literals and print statements
Explain the use of “+” and “*” with strings and numbers
Use the int() and float() functions to convert string input to numbers for computation
Incorporate numeric formatting into print statements
Recognize the four main operations of a computer within a simple Python program
Process:
Create input statements in Python
Create Python code that performs mathematical and string operations
Create Python code that uses assignment statements
Create Python code that formats numeric output
Prior Knowledge
Understanding of Python print and input statements
Understanding of mathematical operations
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 3
Critical Thinking Questions:
Python Program
Flowchart Program
11
Python Activity 3 Part A: Arithmetic Operations and Assignment Statements
1. Execute the print statements in the Python program. What is the output for each statement?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
2. Draw a line between each flowchart symbol and its corresponding line of Python code.
3. Explain the purpose of each arithmetic operation:
a. +
________________________________________________________________________
b. -
________________________________________________________________________
c. *
________________________________________________________________________
d. **
________________________________________________________________________
e. /
_______________________________________________________________________
f.
//
_______________________________________________________________________
g. %
_______________________________________________________________________
FYI: An assignment statement is a line of code that uses a “=” sign. The statement stores the result
of an operation performed on the right-hand side of the sign into the variable memory location
on the lef0hand side.
4. Enter and execute the following two lines of Python code:
age = 15
print(“Your age is”, age)
a. What does the assignment statement: age = 15 do?
______________________________________________________________________________
______________________________________________________________________________
b. What happens if you replace the comma (,) in the print statement with a plus sign (+) and execute
the code again? Why does this happen?
______________________________________________________________________________
______________________________________________________________________________
5.
What is stored in memory after each assignment statement is executed?
Assignment Statement
answer = 6 ** 2 + 3 * 4 // 2
final = answer % 4
Computer Memory
Answer
Final
12
Python Activity 3 Part A: Arithmetic Operations and Assignment Statements
6.
What happens if you try to use the “+” with strings instead of numbers?
Test the following program:
The third line of code contains an assignment statement. What is stored in fullName
when the line is executed?
______________________________________________________________________________
a.
b.
How can you fix the output so that the words are separated?
______________________________________________________________________________
FYI: The “+” concatenates the two strings stored in the variables into one string. The
assignment statement stored the results in the variable fullName. “+” can only be
used when both operators are strings.
c.
What happens when you execute the following code? Why?
______________________________________________________________________________
______________________________________________________________________________
7.
Before entering the following code into the Python interpreter, try to figure out what you think
the statement should print.
Now execute it. What does it do? Is this what you thought it would do?
______________________________________________________________________________
______________________________________________________________________________
8.
Let’s take a look at a program that prompts the user for two numbers and subtracts them.
Execute the following code.
a.
What output do you expect?
_____________________________________________
b.
What is the actual output?
_____________________________________________
c.
Revise the program in the following manner:
Between lines 2 and 3 add the following lines of code:
num1 = int(firstNumber)
num2 = int(secondNumber)
13
Python Activity 3 Part A: Arithmetic Operations and Assignment Statements
Next, replace the statement:
difference = firstNumber – secondNumber
with the statement:
difference = num1 – num2
Execute the program again. What output did you get? ________________________
d.
Explain the purpose of the function int().
______________________________________________________________________________
______________________________________________________________________________
e.
Explain how the changes in the program produced the desired output.
______________________________________________________________________________
______________________________________________________________________________
Application Questions: Use the Python Interpreter to check your work
1.
Write the line of Python code that calculates and prints the answer to the following arithmetic
expressions:
a.
8 to the 4th power
___________________________________________________
b.
The sum of 5 and 6 multiplied by the quotient of 34 and 7 using floating point arithmetic
_______________________________________________________________________
2.
Write an assignment statement that stores the remainder obtained from dividing 87 and 8 in the
variable leftover
______________________________________________________________________________
3.
Assume:
courseLabel = “CMSC”
courseNumber = “190”
Write a line of Python code that concatenates the label with the number and stores the result in
the variable courseName. Be sure that there is a space between the course label and the course
number when they are concatenated.
_________________________________________________________________
4.
Create a program the outputs the total cost of a lunch order. Users should be prompted to input
the number of hamburgers, fries, and drinks they want and the program should print the total cost
of the order. The hamburgers cost 2.00, fries cost 1.50, and drinks cost 1.00. Be creative and
professional in prompting the user for the information and in displaying the output.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
Name: _______________________________________
Partners:
________________________________
Python Activity 3 Part B: Arithmetic Operations and Assignment Statements
“Get the program to compute that!”
Learning Objectives
Students will be able to:
Content:
Incorporate numeric formatting into print statements
Recognize the four main operations of a computer within a simple Python program
Process:
Create Python code that uses assignment statements
Create Python code that formats numeric output
Prior Knowledge
Understanding of Python print and input statements
Understanding of mathematical operations
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 3
Critical Thinking Questions:
1. So far you have not been concerned about formatting output on the screen. Now you will discover
how Python allows a programmer to precisely format output. Some of the differences are very subtle,
so take notice of the differences in outputs.
Start by entering and executing the following code.
a. What is the problem with the manner in which the output is displayed?
_____________________________________________________________________________
______________________________________________________________________________
b. Replace the last line of code with the following:
print("Total cost of laptops: %.2f" % price)
Discuss the change in the output.
_____________________________________________________________________________
______________________________________________________________________________
c. Replace the last line of code with the following:
print("Total cost of laptops: $%.2f" % price)
Discuss the change in the output.
______________________________________________________________________________
______________________________________________________________________________
Python Activity 3 Part B: Arithmetic Operations and Assignment Statements
d. Experiment with the number “.2” in the print statement by substituting the following
numbers and explain the results.
.4
________________________________________________________________________
.0
________________________________________________________________________
.1
________________________________________________________________________
.8
________________________________________________________________________
e. Now try the following numbers in the same print statement. These numbers contain a
whole number and a decimal. Explain the output for each number.
2.5
_______________________________________________________________________
8.2
_______________________________________________________________________
3.1
_______________________________________________________________________
f.
Explain what the formatting code: “%n.nf % variable” does in a print statement where
n.n represents a number.
_____________________________________________________________________________
______________________________________________________________________________
g. Revise the print statement by changing the “f” to “d” and the decimal number to a whole
number. Explain the sample formatting statements:
print("Total cost of laptops: %2d" % price)
print("Total cost of laptops: %10d" % price)
______________________________________________________________________________
______________________________________________________________________________
h. Explain how “%nd % variable” formats numeric data. “n” represents a whole number.
______________________________________________________________________________
______________________________________________________________________________
FYI: Computers perform four main operations on data:
Input data into a computer
Output data to a screen or file
Process data using arithmetic, logical, searching or sorting operations
Store data
2.
Use the following program to answer the questions below.
16
Python Activity 3 Part B: Arithmetic Operations and Assignment Statements
a.
Using the code and comments in the program listed above, explain how the four main
operations are implemented in the program.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
b.
There is one new concept exemplified in this sample program. What is it? From the
corresponding output, determine what it does.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Application Questions: Use the Python Interpreter to check your work
1.
Write one line of Python code that will print the word “Happy!” one hundred times.
______________________________________________________________________________
2.
3.
Assume:
itemCost = input(“Enter cost of item: “)
a.
Write one line of code that calculates the cost of 15 items and stores the result in the
variable totalCost
________________________________________________________________________
b.
Write one line of code that prints the total cost with a label, a dollar sign, and exactly two
decimal places. Sample output: Total cost: $22.50
________________________________________________________________________
height1 = 67850
height2 = 456
Use Python formatting to write two print statements that will produce the following output
exactly at it appears below:
Assume:
______________________________________________________________________________
______________________________________________________________________________
4. You have already completed the following program in a previous activity. Format the output.
Create a program the outputs the total cost of a lunch order. Users should be prompted to input the
number of hamburgers, fries, and drinks they want and the program should print the total cost of the
order. The price of hamburgers is 2.00, fries is 1.50, and drinks is 1.00. Be creative and professional
in prompting the user for the information and in displaying the output.
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
17
Python Activity 3 Part B: Arithmetic Operations and Assignment Statements
Notes and Questions
Make note of any questions you have about Activity 3 on this page.
18
Name: _______________________________________
Partners:
________________________________
Python Activity 4: Predefined Functions
“How can I use the built-in code that is already part of Python?”
Learning Objectives
Students will be able to:
Content:
Explain the purpose of a predefined function
Explain the functions: abs(), pow(), int() round(), random
Explain the math library functions: floor() and ceil()
Explain the use of the import statement
Explain the purpose of a function argument
Process:
Write code that uses predefined functions
Prior Knowledge
Python concepts from Activities 1-3
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 4
Model 1: Predefined functions in Python
print(), round(), abs(), pow(), int(), etc. are known as predefined functions. Information that a function
needs to do its work is sent to the function between the parentheses (). This information is known as an
argument. To use a function, call the function. input(“Enter your name”) is a call to the input function
sending the string “Enter your name” as an argument
Critical Thinking Questions:
10. Circle the predefined functions in the following program.
11. Draw a line between each statement in the Python program and its
corresponding statement in the flowchart.
Python Activity 4: Predefined Functions
12. Enter and execute the Python program on the previous page.
a. What is the output for each statement ?
print(abs(-4.67))
_________________________
print(pow(5,3))
_________________________
print(pow(49,.5))
_________________________
print(int(34.8))
_________________________
print(round(6.9))
_________________________
import random
print(random.randint(1,100)) ___________________
b. What is the difference between the round() function and the int() function?
______________________________________________________________________________
______________________________________________________________________________
4. What is the output for each line of code? Verify your answers by executing the code and explain the
answer given by the interpreter.
a. abs(4.5)
_________________________________________________
b. int(“678”)
_________________________________________________
c. round(-5.6)
_________________________________________________
d. import random
random.randint(4,10)
___________________________________________
What is the purpose of “import random”? What happens if you omit that line of code?
______________________________________________________________________________
______________________________________________________________________________
5.
Write a definition of a predefined function.
______________________________________________________________________________
______________________________________________________________________________
6.
Circle the argument in the following predefined function:
number = 45.78
answer = round(number)
7.
How many arguments can a function have?
8.
answer = pow(4,3). What is/are the argument(s) in this code? ______________________
9.
If a function contains more than one argument, do you think the order of the arguments makes a
difference? Explain your answer.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
_______________________________________
20
Python Activity 4: Predefined Functions
10.
Execute the following code:
import math
x = 4.7
y = 5.3
z = -4.8
a = -3.2
print(math.ceil(x))
print(math.ceil(y))
print(math.ceil(z))
print(math.ceil(a))
print(math.floor(x))
print(math.floor(y))
print(math.floor(z))
print(math.floor(a))
a.
Explain what the ceil() function does.
________________________________________________________________________
________________________________________________________________________
b.
Explain the purpose of the floor() function.
________________________________________________________________________
________________________________________________________________________
c.
Why are the calls to the math() and ceil() functions preceded by “math.”?
________________________________________________________________________
________________________________________________________________________
Application Questions: Use the Python Interpreter to check your work
1.
Write a line of code that prints the integer portion of the number 21.45.
______________________________________________________________________________
2.
Write code that prompts the user for a floating point number and prints the smallest integer that is
larger than the number the user entered.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
3.
Write a line of code that prints a random number between one and 6.
______________________________________________________________________________
______________________________________________________________________________
4.
Assume that a user enters any number and that the number is stored in the variable userNumber.
Write a line of code that converts the input to a float. Then write a line of code that prints the
positive value of the user’s input.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5.
Write a line of code that calculates the square root of 900 and stores the result in the variable
answer.
______________________________________________________________________________
21
Python Activity 4: Predefined Functions
Notes and Questions
Make note of any questions you have about Activity 4 on this page
22
Name: _______________________________________
Partners:
________________________________
Python Activity 5: Boolean Expressions and Selection Statements
“True or False and making choices”
Learning Objectives
Students will be able to:
Content:
Explain the three types of programming structures
Explain how conditional operators and logical operators are used in programming
Use conditional operators with strings and numeric values
Implement the Python syntax of an if/else statement
Determine good test data for programs that include if/else statements
Process:
Write code that includes if statements and if/else statements
Write correct Boolean expressions and compound expressions
Prior Knowledge
Python concepts from Activities 1-4
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 5
Model 1: Programming Structures
Sequence Structure
Decision or Branching Structure
Looping Structure
Critical Thinking Questions:
1.
Each of the flowchart symbols in the chart above represents lines or segments of code. After
examining the chart, write a description of:
a.
sequence structure ________________________________________________________
________________________________________________________________________
b.
decision or branching structure _____________________________________________
_______________________________________________________________________
c.
looping structure
____________________________________________________
________________________________________________________________________
Python Activity 5: Boolean Expressions and Selection Statements
2.
Which structure best describes the types of Python programs you have written so far? Do you
think this structure is the best structure to use for all programs? Why or why not?
______________________________________________________________________________
______________________________________________________________________________
3.
Which structure allows the programmer to create code that decides what code is executed?
_____________________________________________________________________________
Model 2: Conditional Operators
Conditional operators, also known as relational operators, are used to compare the relationship
between two operands. Expressions that can only result in one of two answers are known as
Boolean expression.
4.
Determine the meaning of each of the following conditional operators.
If you are not sure of the meaning of any symbol, create some example
expressions, type them into the Python interpreter (see figure to the
right) and examine the results.
a.
<
___________
b.
>
____________
c.
<=
___________
d.
>=
____________
e.
!=
___________
f.
==
____________
5. What is the result of each of the following expressions?
Assume x = 4, y = 5, z = 4
a.
x>y
______________________________________
b.
x<y
______________________________________
c.
x == y
______________________________________
d.
x != y
______________________________________
e.
x >= z
______________________________________
f.
x <= z
______________________________________
g.
x+y>2*x
______________________________________
h.
y * x – z != 4 % 4 + 16
______________________________________
i.
pow(x,2) == abs(-16)
______________________________________
6. What is the result of the following expressions?
Assume word1 = “hello”, word2 = “good-bye”
a.
word1 == word2
______________________________________
b.
word1 != word2
______________________________________
c.
word1 < word2
______________________________________
d.
word1 >= word2
______________________________________
24
Python Activity 5: Boolean Expressions and Selection Statements
7. Explain how the conditional operators are used when the operands are strings.
______________________________________________________________________________
______________________________________________________________________________
8. There are only two possible answers to the expressions in questions 5 and 6. What are they?
_______________________________________________________________________________
Model 3: IF/ELSE Statement
Flow chart
Python Program
9.
What is the Python code equivalent of the diamond flowchart symbol in the program above?
________________________________________________________________________
10.
Enter and execute the following code. Use various values for the original cost and the sale price.
Explain what the following lines of code do. Each line appears in the program above.
a.
originalPrice = int(originalPriceString)
________________________________________________________________________
b.
percentOff =(originalPrice - salePrice)/originalPrice * 100
________________________________________________________________________
c.
print("Sale price: $%.2f" %salePrice)
________________________________________________________________________
d.
print("Percent off: %2d" % percentOff + "%")
________________________________________________________________________
e.
if percentOff >= 50:
print("You got a great sale!")
________________________________________________________________________
25
Python Activity 5: Boolean Expressions and Selection Statements
11.
Revise the program in #10. If the percent off is 50% or more print “Congratulations!” in addition
to what is already printed. Use a second print statement to do this. Write the code for this part
of the program.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
12.
Revise the program in #12 so that it prints “Done!” when the program is complete – no matter
what the percent off is. How does the placement of this line of code differ from the placement of
the code created for #12?
______________________________________________________________________________
______________________________________________________________________________
Python Program
Flowchart
13.
Compare the flowchart above with the corresponding Python Program. Carefully compare if/else
statement in the two programs. Enter and execute the Python program above.
a.
Test the program at least three times. List the three test data you used and the
corresponding output. Explain why they were the best data to use as a test for the
program.
___________________
__________________
___________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
26
Python Activity 5: Boolean Expressions and Selection Statements
b.
Now you want to add another print statement to the Python program above so that it
printed “That’s really hot!” when the water is 212 degrees or hotter. Rewrite the code
below with this statement included.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
FYI: We can use logical operators to determine logic between conditions (relational expressions).
14.
Sometimes you want to test more than one condition to determine which code segment should be
executed. You can use the following logical operators to create compound conditions. Examine
each operator and a sample of its use. Provide an explanation of how each operator works.
Operator
15.
Example
Explanation
and
(age >= 17) and (hasLicense = = true)
or
(cost < 20.00) or (shipping = = 0.00)
not
not (credits> 120)
Assume the value of the variable numBooks is 40. State the values of each of the Boolean
expression.
Expression
(numBooks > 5) and (numBooks < 100)
Value
(numBooks < 5) or (numBooks > 100)
not(numBooks * 10 == 100)
16.
Suppose you want to determine if a student is ready to graduate. The 3 criteria for graduation are
that the student has earned at least 120 credits, their major GPA is at least 2.0 and their general
GPA is also at least 2.0.
Missing Boolean expression
27
Python Activity 5: Boolean Expressions and Selection Statements
Which Boolean expression would be the correct test for Python code?
a.
numCredits >= 120 or majorGPA >= 2.0 or overallGPA >= 2.0
b.
numCredits > 120 and majorGPA > 2.0 or overallGPA > 2.0
c.
numCredits > 119 and majorGPA >= 2.0 and overallGPA >= 2.0
d.
numCredits >= 120 and majorGPA >= 2.0 and overallGPA >= 2.0
17.
Enter and execute the program in #16. Include your choice for the correct Boolean expression.
Create several data sets to test all possibilities for the Boolean expression. List the data you used
to test all possibilities for the expression.
Data Set
1
2
3
4
5
6
7
8
9
10
numCredits
majorGPA overallGPA
Expression Result (True or False)
Application Questions: Use the Python Interpreter to check your work
1.
Write a Boolean expression that tests if the value stored in the variable num1 is equal to the value
stored in the variable num2.
______________________________________________________________________________
2.
Write a Boolean expression that tests if the value stored in the variable time is less than the value
stored in the variable maxTime or if the value stored in the variable cost is less than the value
stored in the variable maxCost
______________________________________________________________________________
3.
Write the code for an if statement that adds 5 to the variable num1 if the value stored in the
variable testA equals 25. Otherwise subtract 5 from num1.
______________________________________________________________________________
4.
Write the code for an if statement that prints a random number between one and 6 if the value
stored in the variable isValid equals the Boolean value true.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
28
Python Activity 5: Boolean Expressions and Selection Statements
5.
Write a Python program that prompts the user for the cost of two items to be purchased. Then
prompt the user for their payment. If they enter an amount that is less than the total cost of the
two items, print a message that tells them how much they still owe. Otherwise, print a message
that thanks them for their payment and tells them how much change they will receive.
Thoroughly test your code for all possible input.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6.
Write a Python program that prompts the user for a word. If the word comes between the words
apple and pear alphabetically, print a message that tells the user that the word is valid, otherwise,
tell the user the word is out or range.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
7.
Write a Python program that prompts the user for a multiple of 5 between 1 and 100. Print a
message telling the user whether the number they entered is valid.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
29
Python Activity 5: Boolean Expressions and Selection Statements
Notes and Questions
Make note of any questions you have about Activity 5 on this page.
30
Name: _______________________________________
Partners:
Python Activity 6: Functions
________________________________
“Modularizing your code”
Learning Objectives
Students will be able to:
Content:
Explain the meaning and purpose of a function
Recognize a function definition, function header, and function call in a program
Combine the use of functions with if/else statements
Explain programs that use the same function multiple times
Use good test data for programs that include functions
Process:
Write code that includes function definitions and function calls
Write programs that incorporate functions and if/else statements
Prior Knowledge
Python concepts from Activities 1-5
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 6
Critical Thinking Questions:
Python Program
Flowchart
Python Activity 6: Functions
FYI: A function is a segment of code that performs a single task.
1.
Closely examine the flowchart and Python program above.
a.
Draw arrows between each flowchart symbol and the equivalent Python code.
FYI: A function definition is the segment of code that tells the program what to do when the
function is executed. The first line of a function definition is known as the function
header
b.
2.
What Python keyword is used to indicate that a code segment is a function definition?
________________________________________________________________________
c.
What is the function header in the Python code above?
________________________________________________________________________
d.
The name of the function is in the function header. What is the name of the function?
________________________________________________________________________
e.
Examine the Python function. Explain the syntax required for a function: indentation,
etc.
________________________________________________________________________
________________________________________________________________________
f.
Enter and execute the Python program. What is the output?
________________________________________________________________________
g.
What line of code would you add to the program to print the last two lines twice? Where
would you add the code?
________________________________________________________________________
________________________________________________________________________
Examine the following program
a.
Label the function definition and the function call.
b.
The function call and the function definition each include a variable within the
parentheses. The variable in this role is known as an argument. What is the argument in
the function definition? What is its purpose?
________________________________________________________________________
________________________________________________________________________
32
Python Activity 6: Functions
c.
In this example the argument in the function definition and the argument in the function
call have the same name. Is this required?
_______________________________
d.
Enter and execute the program. Verify your answer to question ‘c’ by changing the
variable name in the main program from radius to number. Do not change the variable
name in the function definition. Does the program still work?
__________________
e.
Write a line of code that calls the calculateArea function and sends the value “6” as the
argument. Add the line of code to the main program and execute it to be sure it works
properly. _______________________________________________________________
f.
Add a second function to the program that calculates and prints the diameter of a circle,
given the radius as an argument (parameter). Place the function definition above the main
part of the program. Write the function below.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
g.
Add another line of code to the main part of the program that calls the function that was
created in part ‘f’. Send the radius entered by the user as the argument to the function.
________________________________________________________________________
3.
What is the purpose of a function? Why do programmers use them?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
4.
Carefully examine the following program.
a.
What is the first line of code executed by the Python interpreter?
________________________________________________________________________
33
Python Activity 6: Functions
b.
Enter and execute the program. Use the following test data and indicate what the output
is for each set of data.
Data Set
1
2
3
4
Operand 1
2
3
34
4
Operand 2
6
8
23
5
Operator Result
+
+
/
c.
What problems did you notice when you entered Data Sets 3 and 4?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
d.
Add code to the program that would warn the user about the problems that could occur
when data similar to that in Data Sets 3 and 4 are entered. See sample output below. List
the lines of code below the sample output.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
34
Python Activity 6: Functions
FYI: So far, the functions you have printed any results within the function. They did not send
back any information to the original calling code. Functions that do not send back
information to where they are called are known as void functions. Functions often send
back or return the result and are known as value returning functions.
5.
6.
Enter and execute the code below. Carefully examine the code.
a.
What is the new keyword used in the function definition? What do you think the
keyword tells the program to do?
________________________________________________________________________
________________________________________________________________________
b.
Write the line of code from the program that includes the function call to getSmaller.
________________________________________________________________________
c.
In a void function, the function call is on a line by itself. Why is this function call
placed on the right-hand-side of an assignment statement?
________________________________________________________________________
________________________________________________________________________
d.
What are the arguments used for the function call? _______________________________
Examine the following Python program.
a.
b.
What does the program do?
________________________________________________________________________
Circle the function call. What is different about the placement of the function call?
________________________________________________________________________
35
Python Activity 6: Functions
7.
c.
Is the function a void function or a value returning function? ____________________
d.
Why is the import statement needed in this program?
_______________________________________________________________________
The following Python program performs the same operations and produces the same output as the
previous program. Describe the major differences between the two programs. Edit the previous
program so that it looks like this one and execute it.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Application Questions: Use the Python Interpreter to check your work
1.
Write a function that draws a frog. Call the function to be sure it works. Sample frog:
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
36
Python Activity 6: Functions
2.
Expand the program in #1 to produce the following output.
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
3.
Write a Python program that prompts the user for three words and prints the word that comes last
alphabetically. Use a function to create the program.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
37
Python Activity 6: Functions
Notes and Questions
Make note of any questions you have about Activity 6 on this page.
38
Name: _______________________________________
Partners:
________________________________
Python Activity 7: Nested IF/ELSE Statements
“Decisions, decisions – decisions within decisions!”
Learning Objectives
Students will be able to:
Content:
Explain the purpose of a nested if-else statement
Explain how to use Python if-elif structure
Explain how to test code using Python if-elif structure
Process:
Write code that includes if-elif statements
Write code that uses if-elif statements and functions
Prior Knowledge
Python concepts from Activities 1-6
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 7
Critical Thinking Questions:
1.
Closely examine the flowchart and Python program above.
Python Program
Flowchart
Python Activity 7: Nested IF/ELSE Statements
a. Draw arrows between each flowchart symbol and the equivalent Python code.
b. In the Python code, circle the if/else statement that is nested within another if/else statement.
c. Enter and test the code. List five numbers that you would use to test this program. Indicate
why you chose the numbers.
Number
2.
Why chosen
Enter and execute the following Python program using the same data as you used for #1c.
a. How does the output for this program compare with the output for the previous program?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
b. What new keyword is used in this program? _______________________________________
c. Notice the syntax of this program compared to the previous program. Which program
contains simpler indentation?
_____________________________________________
FYI: elif is the Python keyword that represents else if and allows you to test for one of several options. As
soon as one of the tests is true, the rest are ignored.
d. You can use elif as many times as you need to. Suppose you wanted to add the comment
“Good!” for grades that are between 80 and 89. Where would you add it? Write the code for
this additional choice.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
e. Does the placement of an additional elif clause matter? ______________________________
f.
When is the code associated with the else statement executed?
___________________________________________________________________________
40
Python Activity 7: Nested IF/ELSE Statements
g. Describe how an if/elif/else statement works.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
h.
Change the program in #2 so that it prints the following messages. Write the code below.
Greater than 90
Between 80 and 89
Between 70 and 79
Between 60 and 69”
Less than 60
“Very Good!”
“Good!”
“Satisfactory”
“Fair”
“Poor”
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
i.
3.
Make a final change to the program so that it prints an error message if the grade entered
is greater than 100 or less than 0.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
Is the use of the else statement mandatory when creating an if/elif statement? Explain your
answer.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
41
Python Activity 7: Nested IF/ELSE Statements
Application Questions: Use the Python Interpreter to check your work
1. Write an if/elif statement that assigns a value to the variable bonus depending on the amount of sales.
Assume the amount of the sales is stored in a variable called sales.
Sales
Bonus
>= 100,000
10,000
>= 75,000
5,000
>= 50,000
2,500
>= 25,000
1,000
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
2. Carefully examine and then complete the following Python program. The program prompts the user
to enter a number between 1 and 5 and also generates a random number between 1 and 5. The
program prints the number the user enters and prints the random number. The program then
compares the two numbers. If the numbers are the same, it prints the message “You picked the same
number as the computer!”. If the number the user entered is higher than the random number, the
program should print “Your number is higher than the computer’s number.” Otherwise, it should
print: “Your number is smaller than the computer’s number”.
Explain what the if/else statement does in the Main Program.
42
Python Activity 7: Nested IF/ELSE Statements
.
43
Python Activity 7: Nested IF/ELSE Statements
Notes and Questions
Make note of any questions you have about Activity 7 on this page.
44
Name: _______________________________________
Partners:
________________________________
Python Activity 8: Looping Structures – WHILE Loops
“Repeating code”
Learning Objectives
Students will be able to:
Content:
Explain the three parts of a loop
Explain the syntax of a while loop
Explain sentinel-controlled and counter controlled loops
Explain short-cut operators
Process:
Write code that includes sentinel-controlled and counter controlled loops
Write code that uses short-cut operators
Prior Knowledge
Python concepts from Activities 1-7
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 8
Critical Thinking Questions
1.
Closely examine the flowchart and Python program below.
FYI: A looping structure allows a block of code to be repeated one or more times. A while loop is
one of the two looping structures available in Python.
Python Program
Flowchart
a. Draw arrows between each flowchart symbol and the equivalent Python code.
b. In the Python code, circle all the code associated with the WHILE loop.
Python Activity 8: Looping Structures – WHILE Loops
c. Enter and test the code. What does the line of code: x=x+1 do?
___________________________________________________________________________
d. How does the Python interpreter know what lines of code belong to the loop body?
___________________________________________________________________________
e. Every loop structure requires three actions. Identify the line of code in the Python
program that corresponds to each of the three actions.
 Initialize a variable used in the test condition:
________________________________________________________________________
 Include a test condition that causes the loop to end when the condition is false:
________________________________________________________________________
 Within the loop body, update the variable used in the test condition:
________________________________________________________________________
2.
Enter and execute the following code.
_______________________________
_______________________________
__________________________________________________
_______________________________
__________________________________________________
__________________________________________________
_______________________________
_______________________________
__________________________________________________
_______________________________
__________________________________________________
_______________________________
__________________________________________________
_______________________
__________________________________________________
3.
a.
Beside each line of code below explain what the code does.
b.
Explain the difference between the two print statements.
________________________________________________________________________
________________________________________________________________________
The following code should print the numbers from 1 to 10, but it does not print anything.
Correct the problem.
number = 12
while number <= 10:
print(number)
number = number + 1
4.
Enter and execute the following code:
number = 0
while number <= 10:
print(number)
number = number - 1
a.
Describe the output.
____________________________________________________
46
Python Activity 8: Looping Structures – WHILE Loops
6.
7.
b.
What caused the output to be what it was?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
c.
Does the program end? Why or why not?
________________________________
_______________________________________________________________________
Enter and execute the following code:
number = 1
while number <= 10:
if number % 2 == 0:
print(number, end= "
number = number + 1
")
a.
State the output.
________________________________________________________________________
b.
What caused the output to display on one line?
________________________________________________________________________
________________________________________________________________________
c.
What control structures are used in this code?
________________________________________________________________________
We want to create a program that prompts the user to enter a number between 1 and 10. As long
as the number is out of range the program re-prompts the user for a valid number. Complete the
following steps to write this code.
a.
Write a line of code the prompts the user for number between 1 and 10.
________________________________________________________________________
b.
Write a Boolean expression that tests the number the user entered by the code in step “a.”
to determine if it is not in range.
________________________________________________________________________
c.
Use the Boolean expression created in step “b.” to write a while loop that executes when
the user input is out of range. The body of the loop should tell the user that they entered
an invalid number and prompt them for a valid number again.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
d.
Write a line of code that prints a message telling the user that they entered a valid
number.
________________________________________________________________________
e.
Put the segments of code from steps “a-d” together. Enter and execute the code. Does it
work properly? If not, correct it and test it again.
_________________________
47
Python Activity 8: Looping Structures – WHILE Loops
f.
How many times does the loop execute? ______________________________________
FYI: A looping structure for which you know the number of times it will execute is known as a
count-controlled loop.
8.
Sometimes a programmer does not know how many times data is to be entered. For example,
suppose you want to create a program that adds an unspecified amount of positive numbers
entered by the user. The program stops adding numbers when the user enters a zero or a negative
number. Then the program prints the total. Before creating this program, review the three actions
required for all loops:
a.
Initialize a variable that will be used in the test condition: What will be tested to
determine if the loop is executed or not? Write a line of code that initializes a variable to
be used in the test condition of the loop for this program. The variable should contain a
value entered by the user.
________________________________________________________________________
b.
Include a test condition that causes the loop to end when the condition is false: What is
the test condition for the while loop used in this program?
________________________________________________________________________
c.
Within the loop body, update the variable used in the test condition: Write the code for
the loop body. Include the code to update the variable in the test condition.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
d.
Is this a count-controlled loop? Why or why not?
________________________________________________________________________
e.
Complete the program. Enter and execute the code. Does it work properly? __________
FYI: Short-cut operators provide a concise way of creating assignment statements when the
variable on the left-hand side of the assignment statement is also on the right-hand side. The
addition short-cut operator (+=) is usually used for incrementing a variable.
9.
Enter and execute the following code:
number = 1
number += 3
print(number)
a.
What does the “+=” shortcut operator do?
________________________________________________________________________
b.
The code: x += 5 is equivalent to which of the following lines of code?
x=5
x=x+5
x=y+5
y=x+5
48
Python Activity 8: Looping Structures – WHILE Loops
c.
Replace the operator ‘+=’ with the following shortcut operators and execute the code.
Explain what each operator does.
-=
_________________________________________________________
*=
10.
_________________________________________________________
Enter and execute the following code:
bonus = 25
salary += bonus
print(“Total salary:”, salary)
a.
What is the output of the preceding code? Is it what you expected?
________________________________________________________________________
b.
Edit the code so that it produces valid output.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
c.
As a result of correcting this code segment, what is needed in order for the shortcut
operators to work properly?
_______________________________________________________________________
d.
Is the following line of code valid: 23 += total? Why or why not?
________________________________________________________________________
11.
The following code should print the numbers beginning at 100 and ending with 0. However it is
missing a line of code. Add the missing code, using the shortcut operator. Indicate where the
code belongs.
countdown = 100
while countdown > 0:
print(countdown)
print(“Done!”)
________________________________________________________________________
12.
Enter and execute the following code:
doAgain = "y"
while doAgain == "y":
word = input("Enter a word:")
print("First letter of " + word + " is " + word[0])
doAgain = input("Type ‘y’ to enter another word and anything
else to quit.")
print("Done!")
a.
What does the program do?
________________________________________________________________________
b.
What is the name of the variable used to store the user’s input? ____________________
c.
In the print statement, what does word[0]represent? ___________________________
49
Python Activity 8: Looping Structures – WHILE Loops
d.
If you changed 0 to 1 in word[0]in the print statement above, what is printed?
________________________________________________________________________
e.
When does the program end?
_____________________________________________
FYI: A sentinel-controlled while loop is a loop that repeats the loop body until the user enters a prespecified value.
13.
g.
Why is the loop in this program is an example of a sentinel control loop?
________________________________________________________________________
h.
Examine the print statement in this program:
print("First letter of " + word + " is " + word[0])
What is the purpose of the “+” as part of the argument in the print statement? What
happens if you replace the “+” with a “,”?
________________________________________________________________________
________________________________________________________________________
Examine the code below.
name = “Simone”
cost = 3.56
numApples = 89
What type of data is stored in each variable: (integer, floating point, or string)
name –
__________________________
cost –
__________________________
numApples – __________________________
FYI: A variable that can store only the values True and False is called a Boolean variable.
14.
Given the assignment statement: foundCost = False
What value is stored in the variable foundCost? ________________________________
What type of data is stored in foundCost?
15.
________________________________
Enter and execute the following code:
a.
What type of variable is ‘doAgain’?
50
_______________________________________
Python Activity 8: Looping Structures – WHILE Loops
b.
What does the program do?
________________________________________________________________________
________________________________________________________________________
c.
What does the following line of code do?
maxNum1 = max(num1, num2, num3, num4)
________________________________________________________________________
d.
Experiment with the arguments in the max() function in the program to determine if the
function must have four arguments. Demonstrate your answer.
________________________________________________________________________
________________________________________________________________________
e.
What does the following code in the program do?
if another != 'y':
doAgain = False
________________________________________________________________________
Application Questions: Use the Python Interpreter to check your work
1.
Write a code segment that prompts the user for an even number. As long as the number is
not even, the user should be given a message and prompted again for an even number.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
2.
Write code segment that prompts the user for a letter from ‘a-z’. As long as the character is not
between ‘a-z’, the user should be given a message and prompted again for a letter between ‘a-z’.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
3.
Complete the following program:
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
51
Python Activity 8: Looping Structures – WHILE Loops
Notes and Questions
Make note of any questions you have about Activity 8 on this page.
52
Name: _______________________________________
Partners:
________________________________
Python Activity 9: Looping Structures: FOR Loops
“Another form of loops”
Learning Objectives
Students will be able to:
Content:
Explain the difference between while loop and a FOR loop
Explain the syntax of a FOR loop
Explain how to use the range() function in a FOR loop
Explain an accumulator in a FOR loop
Process:
Write code that includes FOR loop
Write code that uses use FOR loops within functions
Prior Knowledge
Python concepts from Activities 1-8
Understanding of flowchart input symbols
Further Reading
Transitioning from Visual Logic to Python: Chapter 9
Critical Thinking Questions:
4.
Enter and execute the following two Python programs.
WHILE LOOP -- Python Program
FOR LOOP – Python Program
a. What is the output for each program?
___________________________________________________________________________
b. Both programs produce the same output. Which code fragment is more concise?
___________________________________________________________________________
FYI: The Python predefined range() function is used to define a series of numbers and can be used in
a FOR loop to determine the number of times the loop is executed. .
2.
Enter and execute the following code fragments and state the output:
a.
for x in range(5):
print(x, end=” “)
________________________________
b.
for x in range(1,5):
print(x, end=" ")
________________________________
53
Python Activity 9: Looping Structures: FOR Loops
c.
3.
for x in range(3,20,2):
print(x, end=” “)
___________________________
d.
numIterations = 6
for x in range(numIterations):
print(x, end=” “)
___________________________
e.
numIterations = 6
for x in range(1, numIterations+1):
print(x, end=” “)
___________________________
After examining the five code fragments in #2, explain how the range() function works. Include
an explanation of the arguments.
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
FYI: In a FOR loop you can include a list of values in place of the range() function.
4.
5.
Enter and execute the following code.
for x in [3,6,9,12,15,18]:
print(x, end=” “)
a.
Rewrite this code using the range() function.
________________________________________________________________________
________________________________________________________________________
b.
Why would you use the range() function when you could just list the numbers?
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
As you learned in Activity 8, every loop structure requires three actions. Explain how these
actions are implemented in the following Python FOR loop.
for x in range(1,5):
print(x, end=" ")
a.
Initialize a variable used in the test condition;
________________________________________________________________________
b.
Include a test condition that causes the loop to end when the condition is false:
________________________________________________________________________
c.
Within the loop body, update the variable used in the test condition:
________________________________________________________________________
54
Python Activity 9: Looping Structures: FOR Loops
6.
Read through the code and determine what it does.
favorite = input("Enter your favorite ice cream flavor: ")
for x in range(1,5):
print(str(x) + “.”, favorite, end="\t")
a.
Explain what you think the program does.
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
b.
Enter and execute the code to determine if you were correct. What does the program
actually do? Provide a detailed explanation.
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
c.
Explain the use of the str() function in the print statement. Why is it needed?
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
7.
Complete the arguments in the following range function so that the code prints the even
numbers between 100 and 200 inclusive.
for x in range(_____________________________):
print(x)
8.
Complete the arguments in the following range function so that the code prints: 5 4 3 2 1 0.
for x in range(______________________________):
print(x)
FYI: An accumulator is a variable that stores the sum of a group of values.
9.
Examine the following code segment.
total = 0
for x in range(5):
number = int(input("Enter a number: "))
total += number
print("The total is:",total)
a.
Why is the variable total initialized to 0 in the first line of code?
________________________________________________________________________
________________________________________________________________________
b.
Explain what the following code does:
number = int(input("Enter a number: "))
________________________________________________________________________
________________________________________________________________________
55
Python Activity 9: Looping Structures: FOR Loops
10.
c.
Explain what the following code does:
total += number
________________________________________________________________________
________________________________________________________________________
d.
How many numbers does the program prompt for?
e.
What is the accumulator in the code segment?
________________________________________________________________________
__________________________
Is it better to use a FOR loop when you know the number of times the loop should be executed or
when you do not know? Explain your answer.
______________________________________________________________________________
______________________________________________________________________________
Application Questions: Use the Python Interpreter to check your work
1.
Write a code segment using a FOR loop that prints multiples of 5 from 5 to 500.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
2.
Complete the program on the following page. The program should:
Display five addition facts, one at a time, and allow the user to answer them.
Provide the correct answer if user enters incorrect answer.
Print a congratulatory answer, if the answer is correct.
Keep track of the number of problems the user answers correctly.
Prints a special message, if the user gets all five problems correct.
Fill in the missing code; comments (also written below) indicate location of missing code.
# include the required import statement
______________________________________________________________________________
# include a FOR loop that prints the numbers from 10 to 0
______________________________________________________________________________
# Assign a random number between 1 and 10 to num1 and num2
______________________________________________________________________________
# Write the test condition to determine if the user’s
# answer is equal to the sum of the two numbers
______________________________________________________________________________
# Write the line of code to increment the variable
# that is keeping track of the number of correct answers.
______________________________________________________________________________
# Print the addition fact and include the correct answer.
______________________________________________________________________________
56
Python Activity 9: Looping Structures: FOR Loops
# Write the test condition to determine if the user answered
# all the questions correctly
______________________________________________________________________________
# Write the code to call the function that prints the rocket
______________________________________________________________________________
57
Python Activity 9: Looping Structures: FOR Loops
Notes and Questions
Make note of any questions you have about Activity 9 on this page.
58
Name: _______________________________________
Partners:
________________________________
Python Activity 10: Files and Nesting Looping Structures
“Alternative input and loops inside loops”
Learning Objectives
Students will be able to:
Content:
Explain how to open a text file for reading and for writing
Explain the difference between the read() and readline() functions
Explain the purpose of the str() function.
Explain the effect of the arguments of the range function when reading data from a file.
Explain the purpose of the rstrip(), open(), close(), and write() functions
Explain the difference between writing and appending to a file
Read and write nested FOR loops
Identify inner and outer loops
Process:
Write code that opens, writes to and closes a file
Write code that opens, reads from and closes a file
Write code that uses a nested FOR loop
Prior Knowledge
Python concepts from Activities 1-9
Further Reading
Transitioning from Visual Logic to Python: Chapter 10
Critical Thinking Questions:
FYI: In Python, you can access data from a text file as well as from the keyboard. You can create a
text file in any text editing tool. You should only have one data item per line in the file.
5.
Create a text file named sports.txt and enter the sports listed below, one word per line.
Enter and execute the Python program. Be sure the saved program is in the same folder as the
text file.
Python Program
sports.txt file
59
Python Activity 10: Files and Nesting Looping Structures
a.
What does the program do?
_______________________________________________________________________
b.
Explain the purpose and syntax of the first line of code. What does the ‘string argument’
for the function open represent?
_______________________________________________________________________
2.
c.
Replace the function read() with the function readline(). Execute the program again.
What happens?
_______________________________________________________________________
_______________________________________________________________________
d.
Explain the difference between the two functions: read() and readline().
_______________________________________________________________________
_______________________________________________________________________
Enter and execute the following code.
a.
Explain the format and content of the output.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
b.
How does the output from this programs differ from the output of the program that used
the “read()” function? What caused the difference?
________________________________________________________________________
_______________________________________________________________________
c.
What is the subtle difference in the output if the following print statement
replaced the one above? Which is better?
________________________________________________________________________
d.
What does str(index) do in the program above? Why is the str () function necessary?
________________________________________________________________________
________________________________________________________________________
e.
What happens when you change the arguments in the range() function to 1,10?
_______________________________________________________________________
f.
What happens when you change the arguments in the range() function to (0, 30)?
_______________________________________________________________________
60
Python Activity 10: Files and Nesting Looping Structures
g.
What do the results from “f.” and “g.” tell you about the arguments of the range()
function when you are using it in a FOR loop to read data from a file?
________________________________________________________________________
________________________________________________________________________
FYI: The purpose of the rstrip() function is rather subtle. rstrip() returns a copy of the string after all
characters have been stripped from the end of the string (default whitespace characters, EOL
characters, and newline characters).
3.
The following program is slightly different from the program in #2. Enter and execute the
program.
a.
Compare the output from this program to the output in the previous program. What is the
difference?
________________________________________________________________________
b.
What code caused the difference in the output?
________________________________________________________________________
c.
In this example the rstrip() function strips the newline character from the string that is
read from the file. Why is the newline character attached to the end of the string?
________________________________________________________________________
d.
Does the rstrip() function contain any arguments? How does it know what string to act
upon?
________________________________________________________________________
e.
lstrip() is a similar function. What do you think it does?
____________________________________________________
4.
The following program is slightly different from the program in #3. Enter and execute the
program.
a.
What does the program display?
________________________________________________________________________
________________________________________________________________________
b.
How many functions are used in this program? _________________________________
c.
Two functions use what is known as dot(.) notation. What are the two functions?
________________________________________________________________________
61
Python Activity 10: Files and Nesting Looping Structures
d.
5.
Examine the output and explain what the len() function does.
________________________________________________________________________
Enter and execute the following program:
a.
What output appears on the screen?
________________________________________________________________________
b.
What does the program do?
________________________________________________________________________
c.
Locate the file studentInfo.txt on your computer. The file is stored in the same folder as
the program. What is stored in the file?
________________________________________________________________________
d.
What is the purpose of “w” in the following line of code?
________________________________________________________________________
e.
Did you create the file: studentInfo.txt before you included it in the code? ___________
f.
Execute the program again using different input. Open the studentInfo.txt file. What is
in the file? Is the data from the first program execution still there?
________________________________________________________________________
g.
Change the ‘w’ to ‘a’ in the open() function. Execute the program again with different
input. Examine the student Info.txt file. What did ‘a’ as an argument in the open()
function do? What word do you think ‘a’ represents?
________________________________________________________________________
________________________________________________________________________
h.
Notice the new function – write(). How many arguments does the write function have?
________________________________________________________________________
i.
How does the write() function know what file to write to?
________________________________________________________________________
j.
What line of code closes the file? Where is the line of code positioned in the program?
________________________________________________________________________
________________________________________________________________________
62
Python Activity 10: Files and Nesting Looping Structures
k.
Revise the program so that the user can enter three names during one execution of the
program. You may need to change the order of some of the code.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
FYI: A loop within another loop is known as a nest loop. Proper indentation is essential for the
loops to work properly..
6.
6.
Enter and execute the following code:
a.
What does the program display?
________________________________________________________________________
b.
How many FOR loops are in this code? Is one loop completely executed before the next
loop begins? What do you call this type of loop?
________________________________________________________________________
________________________________________________________________________
c.
How many times is the following line of code executed in the program? ______________
d.
In the program listed at #6, above, label the inner loop and the outer loop.
e.
What does the inner loop do?
________________________________________________________________________
f.
What does the outer loop do?
________________________________________________________________________
If you were asked to created a Python program that displayed the adjacent
rectangle, you could easily do it with a set of print statements or a FOR loop
and a print statement. We will go through several steps to create a program that
will print similar output but allows the user to determine the length and width
of the figure when they execute the program.
63
Python Activity 10: Files and Nesting Looping Structures
7.
a.
Create a code segment that prompts the user for a number between 1 and 10 and then
prints that many asterisks (*) on one line. Use a FOR loop.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
b.
You want to create several lines of asterisks. Revise the code in “a.” to also prompt the
user for how many lines to print. Use an “outer” loop to print that many lines of asterisks.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
c.
Edit the program so that it prints numbers instead of asterisks. Write
the line of code that was changed.
________________________________________________________
Examine the following code and determine the output. Indicate the changes in
memory as the program is executed. Assume the user input is 5.
Variable
height
row
column
Memory
Application Questions: Use the Python Interpreter to check your work
1.
Create a text file that contains 10 numbers between 50 and 100. Write a program that reads the
numbers from the file and totals the numbers. The program should print all the numbers and
display the total when all the numbers have been added together. (Warning! The input from the
file will be considered a string. Be sure to convert the input to int or float – just as you do when
numbers are entered from the keyboard.)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
64
Python Activity 10: Files and Nesting Looping Structures
2.
Revise the following program. Allow the user to enter the name of the file and use the input to
open the file.
______________________________________________________________________________
______________________________________________________________________________
3.
Create a Python program that prompts the user for a number and
then prints an inverted right triangle containing that many rows
similar to the output to the right.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
65
Python Activity 10: Files and Nesting Looping Structures
Notes and Questions
Make note of any questions you have about Activity 10 on this page.
66
Name: _______________________________________
Partners:
________________________________
Python Activity 11 Part A: Lists
“More versatile than arrays -- lists”
Learning Objectives
Students will be able to:
Content:
Define a list
Identify elements of a list
Explain the purpose of positive and negative indexes in a list.
Explain how to access individual elements of a list
Explain how the following functions are used with lists: append(), insert(), remove(), count(),
index()
Explain how to replace an item
Process:
Write code that prints a list
Write code that edits a list – add, remove, and insert items
Prior Knowledge
Python concepts from Activities 1-10
Further Reading
Transitioning from Visual Logic to Python: Chapter 11 pp. 95-101
Critical Thinking Questions:
FYI: A sequence is an object that stores multiple data items in a contiguous manner. Two types of
sequences are strings and lists. Each value stored in a list is called an element.
6.
Examine the sample lists below.
Sample Lists in Python
a.
How many elements does the list named digits contain?
___________________
b.
What type of data is stored in each list (String, numeric)?
digits list: __________________________________________________________
fruits list: __________________________________________________________
studentData list:
c.
___________________________________________________
How would you define a list?
_______________________________________________________________________
_______________________________________________________________________
67
Python Activity 11 Part A: Lists
2.
The following line of code prints the first element in the digits list.
a.
What value does fruits[3] represent?
_______________________________________
b.
Enter and type the fruits list and write a line of code that prints the last value.
________________________________________________________________________
c.
Edit your print statement in ‘b’ so that it prints fruits[4]. What is printed? Why?
________________________________________________________________________
d.
Edit your print statement so that it prints fruits[-1]. What is printed?
_______________________________________________________________________
e.
Change -1 to -2 in “d.”. What is printed?
_______________________________________________________________________
FYI: The number used to locate an element in the list is called an index.
3.
f.
Explain how the positive and negative indexes locate the desired elements.
_______________________________________________________________________
_______________________________________________________________________
g.
What is printed with the following print statement: print(fruits)? How is the information
displayed?
_______________________________________________________________________
_______________________________________________________________________
Enter and execute the following code:
a.
What is the output?
_______________________________________________________________________
_______________________________________________________________________
b.
Explain the first line of code especially the code on the right hand side of the equal sign.
________________________________________________________________________
_______________________________________________________________________
c.
Explain why the second line of code produces the same output as the first line above.
________________________________________________________________________
_________________________________________________________________ ______
68
Python Activity 11 Part A: Lists
d.
4.
Add the following line of code to the program: print(len(mult2))
What is the output? What does the len() function do?
_______________________________________________________________________
_______________________________________________________________________
Enter and execute the following code:
a.
What is the output for the second line of code:
________________________________________________________________________
b.
Examine the following code. It contains a FOR loop but does not use the range()
function. In previous FOR loops the values resulting from the range() function were
stored in x during each iteration of the loop.
i.
What is being stored in x for each iteration of the loop in the following code?
________________________________________________________________________
ii.
What is the output for this code?
________________________________________________________________________
c.
What are the similarities and differences between the output for “a.” and “b.”?
_______________________________________________________________________
_______________________________________________________________________
d.
Add each of the following print statements to the code above. What is the output for each
statement? Explain the output.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
69
Python Activity 11 Part A: Lists
5.
6.
7.
8.
Enter and execute the following code:
a.
Explain what the following line of code does: flowers.append(‘gardenia’)
_______________________________________________________________________
_______________________________________________________________________
b.
Write a line of code that would add the flower lavender to the list.
_______________________________________________________________________
Enter and execute the following code:
a.
Explain what the following line of code does: flowers.insert(2,‘lily’)
_______________________________________________________________________
_______________________________________________________________________
b.
Write a line of code that would place the flower: sunflower at the beginning of the list.
_______________________________________________________________________
Enter and execute the following code:
a.
Explain what the following line of code does: del flowers[2]
_______________________________________________________________________
_______________________________________________________________________
b.
Write a line of code that would delete the last flower in the list.
_______________________________________________________________________
Enter and execute the following code:
a.
Explain what the following line of code does: flowers.remove(‘tulip’)
_______________________________________________________________________
_______________________________________________________________________
70
Python Activity 11 Part A: Lists
9.
10.
b.
Write a line of code that would delete ‘daffodil’ from the list.
________________________________________________________________________
c.
Edit the code to determine what happens if the same flower appears in the list twice and
use the remove()function to remove the word. Does it remove both instances of the
word? _________________________________________________________________
d.
Write a line of code that attempts to remove the flower: sweet pea. What happens when
the code is executed?
_______________________________________________________________________
Enter and execute the following code:
a.
Explain what the following line of code does: flowers[1]= ‘freesia’
_______________________________________________________________________
_______________________________________________________________________
b.
Write a line of code that would replace ‘daffodil’ with ‘gardenia’.
_______________________________________________________________________
c.
Explain what the following line of code does: flowers[-3]= ‘lily’
_______________________________________________________________________
_______________________________________________________________________
d.
Explain what happens when the following line of code is added to the program:
flowers[8]= ‘lily’
_______________________________________________________________________
_______________________________________________________________________
Enter and execute the following code:
71
Python Activity 11 Part A: Lists
a.
What is the output of this program?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
b.
Explain the line of code: numY = ballot.count(‘y’)
What does the count() function do? How many arguments does it have?
________________________________________________________________________
c. Add the following lines of code to the program:
What do the lines print? ____________________________________________________
What does the index() function do? _______________________________________
________________________________________________________________________
What happens if you replace ‘y’ or ‘n’ with ‘x’? Why does this happen?
_______________________________________________________________________
_______________________________________________________________________
Application Questions: Use the Python Interpreter to check your work
1.
Create a program that prints a given list, prompts the user for a name and average, adds the new
information to the list and prints the new list. It should produce output similar to the following:
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
7.
Revise the previous program so that it allows the user to enter the name of a person in the list
whose average needs updating and also prompts the user for the new average. The program
should then update the list and print the new list. The program should produce output similar to
the output on the following page:
72
Python Activity 11 Part A: Lists
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
73
Python Activity 11 Part A: Lists
Notes and Questions
Make note of any questions you have about Activity 11A on this page.
74
Name: _______________________________________
Partners:
________________________________
Python Activity 11 Part B: List Functions
“More versatile than arrays -- lists”
Learning Objectives
Students will be able to:
Content:
Explain how the following functions are used with lists: reverse(), sort(), max(), min()
Explain how to use lists with files
Process:
Write code that reverses and sorts lists
Write code the finds the largest or smallest element of a list
Write code that reads from a file into a list
Prior Knowledge
Python concepts from Activities 1-10 and 11_1
Further Reading
Transitioning from Visual Logic to Python: Chapter 11 pp. 101-109
Critical Thinking Questions:
1.
Enter and execute the following code:
a. What does the code print?
___________________________________________________________________________
___________________________________________________________________________
b. What does the reverse() function do?
___________________________________________________________________________
2.
Revise the program in #1 to test each of the following functions.
a. sort function: <listName>.sort()
Write the revised line of code here: ___________________________________________
Does the function make a permanent change to the list? __________________________
Does the function need to be called within an assignment statement?
_____________
b. max function: max(<listName>)
Write the revised line of code here:
_______________________________________
Explain the difference between the call to this function and the call to the sort function.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
75
Python Activity 12: More about Lists and Strings
Does the function need to be called within an assignment statement?
c. min function: min(<listName>)
Write the revised code here:
_____________
_____________________________________________
Is the call to this function similar to the call to the sort function or the max function?
_______________________________________________________________________
Does the function need to be called within an assignment statement?
____________
FYI: The member operation determines if a given item is an element of a list. The operation returns
True if the item is an element of the list and False otherwise. Syntax: <element> in <list name>.
3.
The following program demonstrates the member operation for a list. Enter and execute the
program:
a.
Circle the line of code that uses the member operation.
b.
Edit the program so that if the number the user entered is not in the list, it is added to the
list. Print the list again to be sure the number is added to the list. Here is some sample
output:
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
76
Python Activity 12: More about Lists and Strings
c. Suppose the program prompted the user for two numbers and stored them in the variables
guess1 and guess2. Write the code segment that would print “Super guess!” if the user
entered two numbers in the list.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
4.
Let’s write a program – step by step -- that generates 100 numbers between 1 and 500 and puts
them in a list, prints the numbers, sorts the numbers, reverses the order of the numbers,
determines the number of times a given number is in the list and prints the largest and smallest
number.
a. Create an empty list to store the number
__________________________________
b. Create code to generate 100 numbers
between 1 & 500 store them in the list
__________________________________
__________________________________
__________________________________
c. Create the code to print the list without the
brackets. Create a separate function for
this since you will be printing the list
several times.
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
d. Write the code that sorts and then reverses
the numbers. Print the code after it is
sorted and after the numbers are reversed.
__________________________________
__________________________________
__________________________________
__________________________________
e. Does the order of these two lines of code
matter?
________________________
77
Python Activity 12: More about Lists and Strings
f.
Write the code that prompts the user for a number between 1 and 500 and prints how many
times that number is in the list. If the number is not in the list print the message: “Sorry, your
number is not here!”
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
g. Print the largest and smallest number.
___________________________________________________________________________
___________________________________________________________________________
h. Enter and execute the code from a-e. be sure that it executes properly. List one sample output.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
i.
To make the numbers appear in columns, replace the print statement in the print function with
the following line of code: print("%3d" %x, end=" "). What causes the change in
output format?
___________________________________________________________________________
5.
Enter and execute the following code. What does the program do?
6.
______________________________________________________________________________
______________________________________________________________________________
Add the following code to the program above:
a.
What does the program do once this code is added?
________________________________________________________________________
________________________________________________________________________
b.
Explain the following code:
________________________________________________________________________
78
Python Activity 12: More about Lists and Strings
c.
Explain what the following line of code does:
________________________________________________________________________
d.
Add a final line of code to the program that prints the list.
________________________________________________________________________
Application Question: Use the Python Interpreter to check your work
Complete the missing sections of the following program in the Python interpreter. Most of the code is
missing. Where there is code, comments are needed. First create a text file with several numbers, one on a
line.
79
Python Activity 12: More about Lists and Strings
Notes and Questions
Make note of any questions you have about Activity 11B on this page.
80
Name: _______________________________________
Partners:
________________________________
Python Activity 12: More about Lists and Strings
“Lists and Strings and Functions and more….”
Critical Thinking Questions:
Learning Objectives
Students will be able to:
Content:
Explain how to send a list as an argument to a function
Explain the purpose of the following functions: isalpha(), isdigit(), isspace(), upper(), lower()
Explain what is meant by the fact that “Strings are immutable.”
Demonstrate the use of slicing with strings and lists.
Process:
Write code that uses the following functions: isalpha(), isdigit(), isspace(),
Write code that uses slicing to access elements of a list
Prior Knowledge
Python concepts from Activities 1-11_2
Further Reading
Transitioning from Visual Logic to Python: Chapter 12
1.
2.
At the end of the previous activity you created a function to print a list and passed the list to the
function. Here is another program that includes a function that takes a list as an argument. Enter
and execute the code.
a.
What is the name of the function defined in this program?
b.
What does the function do?
________________________________________________________________________
Enter and execute the following code.
81
___________________
Python Activity 12: More about Lists and Strings
3.
4.
a.
Execute the program with at least five different types of input that include just letters, just
numbers, letters, numbers and other characters. Examine the output for each input. What
does the program do?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
b.
What does the isalpha() function do?
________________________________________________________________________
________________________________________________________________________
Enter and execute the following code.
a.
Execute the program with at least five different types of input. Examine the output for
each input. What does the program do?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
b.
What does the isdigit() function do?
________________________________________________________________________
________________________________________________________________________
Enter and execute the following code.
a.
What does the program do?
________________________________________________________________________
________________________________________________________________________
82
Python Activity 12: More about Lists and Strings
b.
5.
What does the isspace() function do?
________________________________________________________________________
________________________________________________________________________
Enter and execute the following code:
c. Execute the program with the following input and examine the corresponding output.
cmsc190
__________________________________________________________
Cmsc190
__________________________________________________________
CMSC180
__________________________________________________________
CMSC190
__________________________________________________________
d. What does the upper() function do?
__________________________________________________________________________
__________________________________________________________________________
c. Use the lower() function instead of the upper() function in the program above. Revise
the line of code so that it still produces the same output. Execute the program again with the
data listed in ‘a’. (Write the revise code below.)
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
6.
Examine the following code:
a.
b.
What do you think the program prints?
_______________________________________________________________________
_______________________________________________________________________
Enter and execute the code. Does the program do what you thought it did?
_______________________________________________________________________
c.
What would you think the code word[0] = ‘c’ should do? What does it actually do?
_______________________________________________________________________
d.
“Strings are immutable.” From the output you saw when you executed this program,
what do you think this statement means?
_______________________________________________________________________
83
Python Activity 12: More about Lists and Strings
FYI: Slicing is a technique available in Python that allows you to access parts of lists or strings. You
can select multiple elements of a list or string.
Syntax: <listOrStringName>[indexOfFirstItem : indexAfterLastItem].
7.
In this section we are going to try to access parts of a string using slicing. Enter and execute the
following code. Examine the syntax of the code. It uses slicing to access parts of a string.
a.
What is the output for each print statement in the program?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
b.
The first three print statements should be familiar. What does the fourth print statement
do? Explain the meaning of [0:13].
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
c.
What does the following print statement do? Explain the meaning of [16:27].
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
d.
What does the following print statement do? Explain the meaning of [28:].
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
8.
Finally, examine slicing using lists. Enter and execute the following program.
84
Python Activity 12: More about Lists and Strings
a.
What is the output of each print statement in the program?
________________________________________________________________________
________________________________________________________________________
_______________________________________________________________________
________________________________________________________________________
b.
Explain what the following code does.
________________________________________________________________________
________________________________________________________________________
c.
Explain what the following code does:
________________________________________________________________________
________________________________________________________________________
d.
Are lists immutable? Explain your answer.
________________________________________________________________________
________________________________________________________________________
e.
Explain what the following code does:
________________________________________________________________________
________________________________________________________________________
Application Questions: Use the Python Interpreter to check your work
1.
Create a list named “Days” that includes all the days of the week. Print the list.
______________________________________________________________________________
2.
Create a line of code that uses slicing to print the last three days in the list “Days” which you
created in question 1.
______________________________________________________________________________
3.
Create a list named “Vowels” that includes the vowels ‘a’, ‘e’, ‘i’, ‘o’, ‘u’.
______________________________________________________________________________
4.
Use the code in question 3, and create a program that analyzes a user’s input. Complete the
following steps:
a.
Create code that prompts the user for a vowel.
________________________________________________________________________
b.
Create code to determine if the user input is a vowel. If so, congratulate them.
_______________________________________________________________________
________________________________________________________________________
________________________________________________________________________
c.
Create code that determines if it is a letter, but not a vowel and prints a message that
indicates that.
_______________________________________________________________________
________________________________________________________________________
________________________________________________________________________
85
Python Activity 12: More about Lists and Strings
d.
Add code that determines if the user input is a digit instead of a letter, print a message
that indicates that as well.
_______________________________________________________________________
________________________________________________________________________
________________________________________________________________________
e.
Otherwise, tell the user that their input was not a vowel, a letter, or a number.
_______________________________________________________________________
f.
Prevent the program from crashing by terminating the program if the user enters more
than one character. This should actually be tested first.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
g.
Put all the code together and test the program with several sets of data. List a sample
output.
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Notes and Questions
Make note of any questions you have about Activity 12 on this page.
86