zip()函数

一 代码引导：

actions = ['Up', 'Left', 'Down', 'Right', 'Restart', 'Exit']
letter_codes = [ord(ch) for ch in 'WASDRQwasdrq']
for a,n in zip(letter_codes,actions*2):
    print (a,n)

运行结果：

87 Up

65 Left

83 Down

68 Right

82 Restart

81 Exit

119 Up

97 Left

115 Down

100 Right

114 Restart

113 Exit

• 
  

lettercodes_actions = {65: 'Left', 83: 'Down', 68: 'Right', 97: 'Left', 119: 'Up', 114: 'Restart', 81: 'Exit', 82: 'Restart', 115: 'Down', 113: 'Exit', 87: 'Up', 100: 'Right'}
for a,n in dict.items():
    print(a,n)

运行结果：

65 Left

83 Down

68 Right

81 Exit

119 Up

82 Restart

113 Exit

114 Restart

115 Down

97 Left

87 Up

100 Right

两段代码的区别：第一段更灵活

二 zip（）函数作用：

help(zip)



Help on class zip in module builtins:



class zip(object)

 |  zip(iter1 [,iter2 [...]]) --> zip object

 |  

 |  Return a zip object whose .__next__() method returns a tuple where

 |  the i-th element comes from the i-th iterable argument.  The .__next__()

 |  method continues until the shortest iterable in the argument sequence

 |  is exhausted and then it raises StopIteration.

 |  

 |  Methods defined here:

 |  

 |  __getattribute__(self, name, /)

 |      Return getattr(self, name).

 |  

 |  __iter__(self, /)

 |      Implement iter(self).

 |  

 |  __new__(*args, **kwargs) from builtins.type

 |      Create and return a new object.  See help(type) for accurate signature.

 |  

 |  __next__(self, /)

 |      Implement next(self).

 |  

 |  __reduce__(...)

 |      Return state information for pickling.

zip()是内建函数，接受一系列可迭代参数，返回由tupple组成的list。如果参数长度不等，则返回list的长度，和参数长度最短的对象的长度相同。

三 扩展：

python与序列有关的函数有（sorted(),reversed(),enumerate(),zip()）其中，sorted()和zip()返回一个序列（列表）对象，reversed()和enumerate()返回一个迭代器（类似序列）

四 用法：

 1 >>> z1=[1,2,3]

 2 >>> z2=[4,5,6]

 3 >>> result=zip(z1,z2)

 4 >>> result

 5 [(1, 4), (2, 5), (3, 6)]

 6 >>> z3=[4,5,6,7]

 7 >>> result=zip(z1,z3)

 8 >>> result

 9 [(1, 4), (2, 5), (3, 6)]

配合*使用，可以对zip过的对象进行解压

1 >>> zip(*result)

2 [(1, 2, 3), (4, 5, 6)]