Python内置函数(67)——zip
英文文档:
zip
(*iterables)
Make an iterator that aggregates elements from each of the iterables.
Returns an iterator of tuples, where the i-th tuple contains the i-th element from each of the argument sequences or iterables. The iterator stops when the shortest input iterable is exhausted. With a single iterable argument, it returns an iterator of 1-tuples. With no arguments, it returns an empty iterator.
The left-to-right evaluation order of the iterables is guaranteed. This makes possible an idiom for clustering a data series into n-length groups using zip(*[iter(s)]*n)
. This repeats the same iterator n
times so that each output tuple has the result of n
calls to the iterator. This has the effect of dividing the input into n-length chunks.
说明:
1. 函数功能是聚合传入的每个迭代器中相同位置的元素,返回一个新的元组类型迭代器。
>>> x = [1,2,3] >>> y = [4,5,6] >>> xy = zip(x,y) >>> xy #xy的类型是zip类型 <zip object at 0x0429C828> #导入Iterable >>> from collections import Iterable >>> isinstance(xy,Iterable) #判断是否可迭代对象 True >>> list(xy) #结果 [(1, 4), (2, 5), (3, 6)]
2. 如果传入的迭代器长度不一致,最短长度的迭代器迭代结束后停止聚合。
>>> x = [1,2,3] #长度3 >>> y = [4,5,6,7,8] #长度5 >>> list(zip(x,y)) # 取最小长度3 [(1, 4), (2, 5), (3, 6)]
3. 如果只传入一个迭代器,则返回的单个元素元组的迭代器。
>>> list(zip([1,2,3]))
[(1,), (2,), (3,)]
4. 如果不传入参数,则返回空的迭代器。
>>> list(zip())
[]
5. zip(*[iter(s)]*n)等效于调用zip(iter(s),iter(s),...,iter(s))。
>>> x = [1,2,3] >>> list(zip(*[x]*3)) [(1, 1, 1), (2, 2, 2), (3, 3, 3)] >>> list(zip(x,x,x)) [(1, 1, 1), (2, 2, 2), (3, 3, 3)]