1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 HW1: Exercise in Basic Python data structures. Reproduce the following python interactive listing using different data of your choosing, e.g., choose different variable names and data strings other than ‘Bob Smith’ and ‘Sue Jones’ >>> bob = ['Bob Smith', 42, 30000, 'software'] >>> sue = ['Sue Jones', 45, 40000, 'hardware'] >>> bob[0], sue[2] ('Bob Smith', 40000) # fetch name, pay >>> bob[0].split()[-1] 'Smith' # what's bob's last name? >>> sue[2] *= 1.25 >>> sue # give sue a 25% raise ['Sue Jones', 45, 50000.0, 'hardware'] >>> people = [bob, sue ] # reference in list of lists >>> for person in people: print(person) ['Bob Smith', 42, 30000, 'software'] ['Sue Jones', 45, 50000.0, 'hardware'] >>> people[1][0] 'Sue Jones' >>> for person in people: print(person[0].split()[-1]) person[2] *= 1.20 # print last names # give each a 20% raise Smith Jones >>> for person in people: print(person[2]) # check new pay 36000.0 60000.0 >>> pays = [person[2] for person in people] >>> pays # collect all pay [36000.0, 60000.0] >>> pays = map((lambda x: x[2]), people) 3.X) >>> list(pays) [36000.0, 60000.0] # ditto (map is a generator in 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 >>> sum(person[2] for person in people) built-in # generator expression, sum 96000.0 >>> people.append(['Tom', 50, 0, None]) >>> len(people) 3 >>> people[-1][0] 'Tom' >>> NAME, AGE, PAY = range(3) >>> bob = ['Bob Smith', 42, 10000] >>> bob[NAME] # 0, 1, and 2 'Bob Smith' >>> PAY, bob[PAY] (2, 10000) >>> bob = [['name', 'Bob Smith'], ['age', 42], ['pay', 10000]] >>> sue = [['name', 'Sue Jones'], ['age', 45], ['pay', 20000]] >>> people = [bob, sue] >>> for person in people: print(person[0][1], person[2][1]) # name, pay Bob Smith 10000 Sue Jones 20000 >>> [person[0][1] for person in people] # collect names ['Bob Smith', 'Sue Jones'] >>> for person in people: print(person[0][1].split()[-1]) person[2][1] *= 1.10 # get last names # give a 10% raise Smith Jones >>> for person in people: print(person[2]) ['pay', 11000.0] ['pay', 22000.0] >>> for person in people: for (name, value) in person: if name == 'name': print(value) Bob Smith # find a specific field 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 Sue Jones >>> def field(record, label): for (fname, fvalue) in record: if fname == label: return fvalue # find any field by name >>> field(bob, 'name') 'Bob Smith' >>> field(sue, 'pay') 22000.0 >>> for rec in people: print(field(rec, 'age')) # print all ages 42 45 >>> bob = {'name': 'Bob Smith', 'age': 42, 'pay': 30000, 'job': 'dev'} >>> sue = {'name': 'Sue Jones', 'age': 45, 'pay': 40000, 'job': 'hdw'} >>> bob['name'], sue['pay'] # not bob[0], sue[2] ('Bob Smith', 40000) >>> bob['name'].split()[-1] 'Smith' >>> sue['pay'] *= 1.10 >>> sue['pay'] 44000.0 >>> bob = dict(name='Bob Smith', age=42, pay=30000, job='dev') >>> sue = dict(name='Sue Jones', age=45, pay=40000, job='hdw') >>> bob {'pay': 30000, 'job': 'dev', 'age': 42, 'name': 'Bob Smith'} >>> sue {'pay': 40000, 'job': 'hdw', 'age': 45, 'name': 'Sue Jones'} >>> >>> >>> >>> >>> >>> sue = {} sue['name'] sue['age'] sue['pay'] sue['job'] sue = = = = 'Sue Jones' 45 40000 'hdw' 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 {'job': 'hdw', 'pay': 40000, 'age': 45, 'name': 'Sue Jones'} >>> names = ['name', 'age', 'pay', 'job'] >>> values = ['Sue Jones', 45, 40000, 'hdw'] >>> list(zip(names, values)) [('name', 'Sue Jones'), ('age', 45), ('pay', 40000), ('job', 'hdw')] >>> sue = dict(zip(names, values)) >>> sue {'job': 'hdw', 'pay': 40000, 'age': 45, 'name': 'Sue Jones'} >>> fields = ('name', 'age', 'job', 'pay') >>> record = dict.fromkeys(fields, '?') >>> record {'job': '?', 'pay': '?', 'age': '?', 'name': '?'} >>> bob {'pay': 30000, 'job': 'dev', 'age': 42, 'name': 'Bob Smith'} >>> sue {'job': 'hdw', 'pay': 40000, 'age': 45, 'name': 'Sue Jones'} >>> people = [bob, sue] # reference in a list >>> for person in people: print(person['name'], person['pay'], sep=', ') # all pay Bob Smith, 30000 Sue Jones, 40000 >>> for person in people: if person['name'] == 'Sue Jones': print(person['pay']) # fetch sue's pay 40000 >>> names = [person['name'] for person in people] >>> names # collect names ['Bob Smith', 'Sue Jones'] >>> list(map((lambda x: x['name']), people)) # ditto, generate ['Bob Smith', 'Sue Jones'] >>> sum(person['pay'] for person in people) 70000 >>> for person in people: # sum all pay 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 print(person['name'].split()[-1]) person['pay'] *= 1.10 # last name # a 10% raise Smith Jones >>> for person in people: print(person['pay']) 33000.0 44000.0 >>> bob2 = {'name': 'age': 'job': 'pay': {'first': 'Bob', 'last': 'Smith'}, 42, ['software', 'writing'], (40000, 50000)} >>> bob2['name'] # bob's full name {'last': 'Smith', 'first': 'Bob'} >>> bob2['name']['last'] # bob's last name\ 'Smith' >>> bob2['pay'][1] # bob's upper pay 50000 >>> for job in bob2['job']: print(job) # all of bob's jobs software writing >> bob2['job'][-1] # bob's last job 'writing' >>> bob2['job'].append('janitor') # bob gets a new job >>> bob2 {'job': ['software', 'writing', 'janitor'], 'pay': (40000, 50000), 'age': 42, 'name': {'last': 'Smith', 'first': 'Bob'}} >>> bob = dict(name='Bob Smith', age=42, pay=30000, job='dev') >>> sue = dict(name='Sue Jones', age=45, pay=40000, job='hdw') >>> bob {'pay': 30000, 'job': 'dev', 'age': 42, 'name': 'Bob Smith'} >>> db = {} >>> db['bob'] = bob >>> db['sue'] = sue # reference in a dict of dicts 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 >>> db['bob']['name'] # fetch bob's name 'Bob Smith' >>> db['sue']['pay'] = 50000 >>> db['sue']['pay'] # change sue's pay # fetch sue's pay 50000 >>> db {'bob': {'pay': 30000, 'job': 'dev', 'age': 42, 'name': 'Bob Smith'}, 'sue': {'pay': 50000, 'job': 'hdw', 'age': 45, 'name': 'Sue Jones'}} >>> import pprint >>> pprint.pprint(db) {'bob': {'age': 42, 'job': 'dev', 'name': 'Bob Smith', 'pay': 30000}, 'sue': {'age': 45, 'job': 'hdw', 'name': 'Sue Jones', 'pay': 50000}} >>> for key in db: print(key, '=>', db[key]['name']) bob => Bob Smith sue => Sue Jones >>> for key in db: print(key, '=>', db[key]['pay']) bob => 30000 sue => 50000 >>> for key in db: print(db[key]['name'].split()[-1]) db[key]['pay'] *= 1.10 Smith Jones >>> for record in db.values(): print(record['pay']) 33000.0 55000.0 >>> x = [db[key]['name'] for key in db] >>> x ['Bob Smith', 'Sue Jones'] >>> x = [rec['name'] for rec in db.values()] >>> x ['Bob Smith', 'Sue Jones'] 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 >>> db['tom'] = dict(name='Tom', age=50, job=None, pay=0) >>> db['tom'] {'pay': 0, 'job': None, 'age': 50, 'name': 'To'} >>> db['tom']['name'] 'Tom' >>> list(db.keys()) ['bob', 'sue', 'tom'] >>> len(db) 3 >>> [rec['age'] for rec in db.values() [42, 45, 50]