Python学习 代码 三

>>> 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])

Bob Smith 10000
Sue jones 20000
>>> [person[0][1] for person in people]
['Bob Smith', 'Sue jones']
>>>
>>> for person in people:
for(name,value) in person:
if name=='name':print(value)

Bob Smith
Sue jones
>>>
>>> def field(record,label):
for(fname,fvalue) in record:
if fname==lavel:
return fvalue

>>> field(bob,'name')
Traceback (most recent call last):
File "<pyshell#17>", line 1, in <module>
field(bob,'name')
File "<pyshell#16>", line 3, in field
if fname==lavel:
NameError: global name 'lavel' is not defined
>>> def field(record,label):
for(fname,fvalue) in record:
if fname==label:
return fvalue

>>> field(bob,'name')
'Bob Smith'
>>> field(sue,'pay')
20000
>>>
>>> for rec in people:
print(field(rec,'age'))

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']
('Bob Smith', 40000)
>>> bob['name'].split()[-1]
'Smith'
>>> sue['pay']*=1.10
>>> sue['pay']
44000.0
>>>

>>> bob=dict(name='Bob Smith',age=42,pay=3000,job='dev')
>>> sue=dict(name='Sue Jones',age=45,pay=40000,job='hdw')
>>> bob
{'pay': 3000, 'job': 'dev', 'name': 'Bob Smith', 'age': 42}
>>> sue
{'pay': 40000, 'job': 'hdw', 'name': 'Sue Jones', 'age': 45}
>>>
>>> sue={}
>>> sue['name']='Sue Jones'
>>> sue['age']=45
>>> sue['pay']=40000
>>> sue['job']='hdw'
>>> sue
{'pay': 40000, 'job': 'hdw', '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
{'pay': 40000, 'job': 'hdw', 'age': 45, 'name': 'Sue Jones'}
>>>
>>>
>>> fields=('name','age','job','pay')
>>> record=dict.fromkeys(fields,'?')
>>> record
{'pay': '?', 'job': '?', 'age': '?', 'name': '?'}
>>>
>>>
>>> bob
{'pay': 3000, 'job': 'dev', 'name': 'Bob Smith', 'age': 42}
>>> sue
{'pay': 40000, 'job': 'hdw', 'age': 45, 'name': 'Sue Jones'}
>>>
>>> people=[bob,sue]
>>> for person in people:
print(person['name'],person['pay'],sep=', ')

Bob Smith, 3000
Sue Jones, 40000
>>>
>>> for person in people:
if person['name']=='Sue Jones':
print(person['pay'])

40000
>>>
>>> names=[person['name'] for person in people]
>>> names
['Bob Smith', 'Sue Jones']
>>> list(map((lambda x:x['name']),people))
['Bob Smith', 'Sue Jones']
>>>
>>> sum(person['pay'] for person in people)
43000
>>>
>>>
>>> [rec['name'] for rec in people if rec['age']>43]
['Sue Jones']
>>>
>>> [(rec['age']**2 if rec['age']>=45 else rec['age']*2) for rec in people]
[84, 2025]
>>> G=(rec['name'] for rec in people if rec['age']>40)
>>> next(G)
'Bob Smith'
>>> next(G)
'Sue Jones'
>>> next(G)
Traceback (most recent call last):
File "<pyshell#95>", line 1, in <module>
next(G)
StopIteration
>>> G =((rec['age']**2 if rec['age']>=45 else rec['age']*2) for rec in people)
>>> G.__next__()
84
>>> G.__next__()
2025
>>>
>>> for person in people:
print(person['name'].split()[-1])
person['pay']*=1.10

Smith
Jones
>>> for person in people:print(person['pay'])

3300.0000000000005
44000.0
>>>