python3中zip详解

描述
zip() 函数用于将可迭代的对象作为参数，将对象中对应的元素打包成一个个元组，然后返回由这些元组组成的列表。如果各个迭代器的元素个数不一致，则返回列表长度与最短的对象相同，利用 * 号操作符，可以将元组解压为列表。
语法
zip([iterable, ...])
参数
iterabl -- 一个或多个迭代器;
返回值
返回元组列表。

a1 = [1,2,3]
a2 = [4,5,6]
a3 = [7,8,9]
a4 = ['a','b','c','d']

zip1 = zip(a1, a2, a3) #压缩为元组
for item in zip1:
    print(item)

'''
    (1, 4, 7)
    (2, 5, 8)
    (3, 6, 9)
'''

a1 = [1,2,3]
a2 = [4,5,6]
a3 = [7,8,9]
a4 = ['a','b','c','d']

zip2 = zip(a1, a2, a4) # 以元素个数最少的列表作为长度
for item in zip2:
    print(item)

'''
(1, 4, 'a')
(2, 5, 'b')
(3, 6, 'c')

'''

a1 = [1,2,3]
a2 = [4,5,6]
a3 = [7,8,9]
a4 = ['a','b','c','d']

zip3=zip(a4)
for item in zip3:
    print(item)

'''
('a',)
('b',)
('c',)
('d',)
'''

a1 = [1,2,3]
a2 = [4,5,6]
a3 = [7,8,9]
a4 = ['a','b','c','d']

zip4 = zip(*a4 * 3) # zip(*) 代表解压，与zip()功能相反  *3代表输出3倍

for item in zip4:
    print(item)

#二维矩阵变换(矩阵的行列互换)

l1=[[1,2,3],[4,5,6],[7,8,9]]
print([[j[i] for j in l1] for i in range(len(l1[0])) ])

for item in zip(*l1): # 与 zip 相反，可理解为解压，返回二维矩阵式
    print(item)

'''
[[1, 4, 7], [2, 5, 8], [3, 6, 9]]
(1, 4, 7)
(2, 5, 8)
(3, 6, 9)

'''