Python中zip()函数用法
定义：zip([iterable, …])
zip()是Python的一个内建函数，它接受一系列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tuple（元组），然后返回由这些tuples组成的list（列表）。若传入参数的长度不等，则返回list的长度和参数中长度最短的对象相同。利用*号操作符，可以将list unzip（解压），看下面的例子就明白了：
>>> a = [1,2,3,4] >>> b = [5,6,7,8] >>> c = [5,6,7,8,9,10] >>> test_zip = zip(a,b) >>> test_zip [(1, 5), (2, 6), (3, 7), (4, 8)] >>> test_zip1 = zip(a,c) >>> test_zip1 [(1, 5), (2, 6), (3, 7), (4, 8)] >>> test_zip2 = zip(b,c) >>> test_zip2 [(5, 5), (6, 6), (7, 7), (8, 8)] >>> zip(*test_zip) [(1, 2, 3, 4), (5, 6, 7, 8)] >>>
>>> zip(a,b,c) [(1, 5, 5), (2, 6, 6), (3, 7, 7), (4, 8, 8)] >>>
例子2：
>>> name ('jack', 'beginman', 'sony', 'pcky') >>> age (2001, 2003, 2005, 2000) >>> for n,a in zip(name, age): ... print n ,a ... jack 2001 beginman 2003 sony 2005 pcky 2000 >>>
再看一例：
>>> all={"jack":2001,"beginman":2003,"sony":2005,"pcky":2000}
>>> for i in all.keys():
... print i, all[i]
...
sony 2005
pcky 2000
jack 2001
beginman 2003
>>>
zip()函数：
它是Python的内建函数，(与序列有关的内建函数有：sorted()、reversed()、enumerate()、zip()),其中sorted()和zip()返回一个序列(列表)对象，reversed()、enumerate()返回一个迭代器(类似序列)
>>> z1 = [1,2,3] >>> z2 = [4,5,6] >>> result = zip(z1,z2) >>> result [(1, 4), (2, 5), (3, 6)] >>> z3 = [4,5,6,7] >>> result = zip(z1,z3) >>> result [(1, 4), (2, 5), (3, 6)] >>>
zip()配合*号操作符,可以将已经zip过的列表对象解压：
>>> result [(1, 4), (2, 5), (3, 6)] >>> >>> zip(*result) [(1, 2, 3), (4, 5, 6)] >>> result [(1, 4), (2, 5), (3, 6)] >>>
更近一层的了解：
内容来源：http://www.cnblogs.com/diyunpeng/archive/2011/09/15/2177028.html
* 二维矩阵变换（矩阵的行列互换） 比如我们有一个由列表描述的二维矩阵 a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] 通过python列表推导的方法，我们也能轻易完成这个任务 print [ [row[col] for row in a] for col in range(len(a[0]))] [[1, 4, 7], [2, 5, 8], [3, 6, 9]] 另外一种让人困惑的方法就是利用zip函数： >>> a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] >>> zip(*a) [(1, 4, 7), (2, 5, 8), (3, 6, 9)] >>> map(list,zip(*a)) [[1, 4, 7], [2, 5, 8], [3, 6, 9]] zip函数接受任意多个序列作为参数，将所有序列按相同的索引组合成一个元素是各个序列合并成的tuple的新序列，新的序列的长度以参数中最短的序列为准。另外(*)操作符与zip函数配合可以实现与zip相反的功能，即将合并的序列拆成多个tuple。 ①tuple的新序列 >>>>x=[1,2,3],y=['a','b','c'] >>>zip(x,y) [(1,'a'),(2,'b'),(3,'c')] ②新的序列的长度以参数中最短的序列为准. >>>>x=[1,2],y=['a','b','c'] >>>zip(x,y) [(1,'a'),(2,'b')] ③(*)操作符与zip函数配合可以实现与zip相反的功能,即将合并的序列拆成多个tuple。 >>>>x=[1,2,3],y=['a','b','c'] >>>>zip(*zip(x,y)) [(1,2,3),('a','b','c')]
其它高级运用：
1.zip打包解包列表和倍数 >>> a = [1, 2, 3] >>> b = ['a', 'b', 'c'] >>> z = zip(a, b) >>> z [(1, 'a'), (2, 'b'), (3, 'c')] >>> zip(*z) [(1, 2, 3), ('a', 'b', 'c')] 2. 使用zip合并相邻的列表项 >>> a = [1, 2, 3, 4, 5, 6] >>> zip(*([iter(a)] * 2)) [(1, 2), (3, 4), (5, 6)] >>> group_adjacent = lambda a, k: zip(*([iter(a)] * k)) >>> group_adjacent(a, 3) [(1, 2, 3), (4, 5, 6)] >>> group_adjacent(a, 2) [(1, 2), (3, 4), (5, 6)] >>> group_adjacent(a, 1) [(1,), (2,), (3,), (4,), (5,), (6,)] >>> zip(a[::2], a[1::2]) [(1, 2), (3, 4), (5, 6)] >>> zip(a[::3], a[1::3], a[2::3]) [(1, 2, 3), (4, 5, 6)] >>> group_adjacent = lambda a, k: zip(*(a[i::k] for i in range(k))) >>> group_adjacent(a, 3) [(1, 2, 3), (4, 5, 6)] >>> group_adjacent(a, 2) [(1, 2), (3, 4), (5, 6)] >>> group_adjacent(a, 1) [(1,), (2,), (3,), (4,), (5,), (6,)] 3.使用zip和iterators生成滑动窗口 (n -grams) >>> from itertools import islice >>> def n_grams(a, n): ... z = (islice(a, i, None) for i in range(n)) ... return zip(*z) ... >>> a = [1, 2, 3, 4, 5, 6] >>> n_grams(a, 3) [(1, 2, 3), (2, 3, 4), (3, 4, 5), (4, 5, 6)] >>> n_grams(a, 2) [(1, 2), (2, 3), (3, 4), (4, 5), (5, 6)] >>> n_grams(a, 4) [(1, 2, 3, 4), (2, 3, 4, 5), (3, 4, 5, 6)] 4.使用zip反转字典 >>> m = {'a': 1, 'b': 2, 'c': 3, 'd': 4} >>> m.items() [('a', 1), ('c', 3), ('b', 2), ('d', 4)] >>> zip(m.values(), m.keys()) [(1, 'a'), (3, 'c'), (2, 'b'), (4, 'd')] >>> mi = dict(zip(m.values(), m.keys())) >>> mi {1: 'a', 2: 'b', 3: 'c', 4: 'd'}