Extra Material, Week 10
Names
Programs can be made easier by using Named Ranges which corresponds to the Names collection in VBA.
The following examples are to be used with the Exams worksheet in week10.xls
Creating a named range
There is a simple way if your code preselects a region and then:
Selection.Name="Nametext"
where Nametext is your choice of name.
The Add method is the usual way to create a name e.g.
Names.Add Name:="ExamMarks", RefersTo:="=Exams!$A$2:$D$10"
The RefersTo property must be specified in A1 style notation, including dollar signs where appropriate.
However, the macro recorder generates this code to create a Name
Sub Macro2()
ActiveWorkbook.Names.Add Name:="ExamMarks", RefersToR1C1:= _
"=Exams!R2C1:R10C4"
End Sub
The RefersToR1C1 property is used to reference ranges in a different notation, e.g. R1C8 refers to the first
row eighth column of the worksheet, i .e. cell H1. Therefore it is still an absolute reference.
Selecting a named range
You can select a range with a statement like
Range("ExamMarks").Select
assuming the range is on the active sheet.
However, the macro recorder records the line above as
Application.GoTo Reference:= "ExamMarks"
This alternative way is in fact essential if you want to select a named range that is not on the active
sheet.
GoTo
can also be usde a statement like:
Application.Goto Reference:="R1C8"
which is equivalent to Range("H1").Select
One advantage of using GoTo is that it has the capacity to ‘remember’ the address of the range you start
from, therefore there is the potential to make a macro return to a given location on a worksheet. The
command for this is Application.GoTo
The following macro assumes A2:D10 on the worksheet Exams is a range named ExamMarks. What it does is
loop through the totals and copies the higher ones and pastes to column H. The totals are the result of a
formula and therefore need Paste Special
Sub ExtractHighScores()
Dim i As Integer
i = 1
Worksheets("Exams").Activate
Range("ExamMarks").Columns(4).Select
Do
If ActiveCell.Value >= 100 Then
ActiveCell.Copy
Application.Goto Reference:="R" & i & "C8"
Selection.PasteSpecial Paste:=xlPasteValues
Application.CutCopyMode = False
i = i + 1
Application.Goto
i is 1 to start with; concatenate i to build a
reference to location where we want to
paste.
i must be incremented for next pass of loop
GoTo returns to cell that was copied from
1
End If
ActiveCell.Offset(1, 0).Select
Loop Until ActiveCell = ""
End Sub
If you want to copy and paste both the name and mark to the new location there is only one alteration
to make. The line ActiveCell.Copy (line 9) becomes
Union(ActiveCell, ActiveCell.Offset(0, -3)).Copy
It’s useful to step through this macro and watch it work.
Use the macro recorder to make a chart
Click the Insert tab on the ribbon and start recording a macro. Click the Column button and choose the
first 2D column chart in the window that follows.
Stop recording, delete the chart, but keep the code. The code has potential for re-use if you change the
reference to the range. Excel 2007/10 code is shorter than what follows, but I’ve retained the code from
the Chart Wizard so you can see the way to change the Chart Title and remove the legend.
Sub MakeChart()
Selection.CurrentRegion.Select
Charts.Add
ActiveChart.ChartType = xlColumnClustered
ActiveChart.SetSourceData Source:=Sheets("Exams").Range("A1:B10"), PlotBy:= _
xlColumns
ActiveChart.Location Where:=xlLocationAsObject, Name:="Exams"
With ActiveChart
.HasTitle = True
.ChartTitle.Characters.Text = "Exam Marks"
.Axes(xlCategory, xlPrimary).HasTitle = False
.Axes(xlValue, xlPrimary).HasTitle = False
End With
ActiveChart.HasLegend = False
End Sub
Here is the suggested chart code for this exercise:
Sub MakeExamChart()
Dim chartdata As Range
Set chartdata = Selection.CurrentRegion
ActiveSheet.Shapes.AddChart.Select
ActiveChart.SetSourceData Source:= chartdata
ActiveChart.ChartType = xlColumnClustered
ActiveChart.HasTitle = True
ActiveChart.ChartTitle.Text = "High Scores"
ActiveChart.HasLegend = False
End Sub
We are at the point of being able to extract the high exam scores, paste them to another region, and
chart them. You could now put it all together as follows:
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Sub ExtractAndChart()
ExtractHighScores
Range("H1").Select
MakeExamChart
End Sub
‘ keyword Call is optional
Redefining a named range after adding data to it
There is no method that ‘redefines’ the address of an existing named range, for example, once you
have added or deleted data from it. What you do is to use Names.Add to add the range again with the
updated dimensions. Rather than struggling to concatenate the update literal range reference an easier
way is to make your code select the range, then use a reference to Selection for the RefersTo argument.
For example,
Names.Add Name:="ExamMarks", RefersTo:= Selection
which could be written more tersely
Names.Add "ExamMarks", Selection
There are other ways to accomplish this, e.g. code for the form on the worksheet Data in week 10 uses
concatenation.
Creating Names from a Selection
There is a very efficient way to create names from existing worksheet data. Given a selectiont as
illustrated below . . .
. . . select the Formulas ribbon, click Create from Selection
and if you select only the Top Row checkbox, Excel will create names from each of the selected
column headings i.e. Date, Open, High and so on.
The code for this is would be:
Selection.CreateNames Top:=True, Left:=False, Bottom:=False, Right:=False
Working with two ranges in parallel
It is possible to process two (or more) ranges in parallel by using the same loop. Using the ftse worksheet,
there are two named ranges Close03 and Close02. The following program simply colours the font red if the
closing price for each month in 2003 is lower than for the corresponding month in 2002, and green if it is
higher.
The code takes advantage of the fact that the two ranges are of the same size and can use the count
property of one or the other as the upper bound of the For loop:
For i = 1 To close03.count
On the other hand you might have to code a test to see which range is larger, if for example you were
comparing one month’s prices of a share with the corresponding month the previous year (there may have
been less or more trading days).
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Sub CompareRanges()
Dim i As Integer
Dim close03 As Range, close02 As Range
Set close03 = Range("Close2003")
Set close02 = Range("Close2002")
For i = 1 To close03.count
If close03(i) < close02(i) Then
close03(i).Font.Color = vbRed
Else
close03(i).Font.Color = vbGreen
End If
Next i
End Sub
Note also the use of range variables using Set, which makes the code more compact. Compare the above
For loop with the following code that works with the ranges directly:
For i = 1 To Range("Close2003").Cells.count
If Range("Close2003").Cells(i) < Range("Close2002").Cells(i) Then
Range("Close2003")(i).Font.Color = vbRed
End If
Next i
Resize property of a range
A range has a resize property, which will seem intimidating to beginners. However, with a little
thought it can be understood and used. Here is an example which demonstrates it, though is not
terribly useful. The code resizes a selection by one row and one column.
Sub ResizeDemo()
Dim numrows As Integer
Dim numcolumns As Integer
numrows = Selection.Rows.Count
numcolumns = Selection.Columns.Count
Selection.Resize(numrows + 1, numcolumns + 1).Select
' omit either row or column argument to leave size as it is
End Sub
Now consider this selection:
The statement
Selection.Offset(1,0).Select
has the following effect
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which isn’t quite the answer. However this reference can be resized to get rid of the last blank row and
effectively you have an expression to select a selection without its header which would be ideal for
copy and paste operations.
Sub SelectWithoutHeader()
'resizes table of data so it 'loses' the header
Dim tbl As Range
Set tbl = ActiveCell.CurrentRegion
tbl.Offset(1, 0).Resize(tbl.Rows.Count - 1, _
tbl.Columns.Count).Select
End Sub
Can you determine whether the active cell is in a particular named range?
Yes, with some difficulty. Assuming you want to test if the active cell is in a named range called
ExamMarks then the following expression gives True
Union(ActiveCell,Range("ExamMarks")).Address = Range("ExamMarks").Address
Worksheet_Change Event
The Change event of a worksheet happens when data is changed. This could be by means of an
external data link like Bloomberg.
Assuming a named range called Prices, here is a program that changes the colour of numeric cells; the
code is triggered by a change to the value of any cell on the worksheet.
Private Sub Worksheet_Change(ByVal Target As Range)
Dim r As Range
For Each r In Range("prices")
If IsNumeric(r) And Not IsEmpty(r) Then
If r >= 16 Then
r.Font.Color = vbGreen
ElseIf r < 15 Then
r.Font.Color = vbRed
Else
r.Font.Color = vbBlack
End If
End If
Next r
End Sub
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Tutorial: Make a Line Chart
We will create data to work out the cosine of an angle then make a line chart from it.
First the code to create the data.
Sub
Dim
Set
Dim
For
MakeData()
startcell As Range
startcell = ActiveCell
i As Integer
i = -180 To 180 Step 15
ActiveCell = i
ActiveCell.Font.Bold = True
ActiveCell.Offset(1, 0) = Round(Cos(Degree2Radian(ActiveCell)), 3)
ActiveCell.Offset(0, 1).Select
Next i
startcell.Select
startcell.CurrentRegion.Columns.AutoFit
End Sub
Also need this function to convert the degrees to radians.
Function Degree2Radian(z As Single) As Single
' excel's trig. functions work with radians not degrees hence need to convert
Degree2Radian = z * WorksheetFunction.Pi / 180
End Function
Code to create the chart, assuming the data is in B7:B8
Sub MakeWave1()
'assumes data is B7:Z8
ActiveSheet.Shapes.AddChart.Select
ActiveChart.ChartType = xlLine
ActiveChart.SetSourceData Source:=Range("'Sheet2'!$B$8:$Z$8")
'recorded code to modify the axis
ActiveChart.SeriesCollection(1).XValues = "='Sheet2'!$B$7:$Z$7"
'every second label otherwise looks cramped
ActiveChart.Axes(xlCategory).TickLabelSpacing = 2
ActiveChart.HasLegend = False
End Sub
This is a more general solution; you should study the difference to the above.
Sub MakeWave2()
'assumes active cell is in the data to be charted
Dim r As Range
Set r = Selection.CurrentRegion
ActiveSheet.Shapes.AddChart.Select
ActiveChart.ChartType = xlLine
ActiveChart.SetSourceData Source:=r.Rows(2)
'recorded code to modify the axis
ActiveChart.SeriesCollection(1).XValues = r.Rows(1)
'every second label otherwise looks cramped
ActiveChart.Axes(xlCategory).TickLabelSpacing = 2
ActiveChart.HasLegend = False
End Sub
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How to modify the chart in Excel; you could record these steps to get the code.
1.
Initial appearance of chart
2.
Right-click and choose Select Data
3.
Select Series1 and click Remove
4.
Series2 is visible; next we format the x-axis
5.
Choose Select Data as in step 2, click the Edit
button on the right
6.
Select the range that contains the axis. You should
see the labels. Click OK
7.
Right-click the horizontal axis and choose Format
Axis. Click Specify interval unit, type 2. Close.
8.
Remove the legend manually and the chart is
complete
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