zoukankan      html  css  js  c++  java
  • python zip()

    >>> help(zip)
    Help on built-in function zip in module __builtin__:
    
    zip(...)
        zip(seq1 [, seq2 [...]]) -> [(seq1[0], seq2[0] ...), (...)]
        
        Return a list of tuples, where each tuple contains the i-th element
        from each of the argument sequences.  The returned list is truncated
        in length to the length of the shortest argument sequence.
    
    >>> list_1 = ['name', 'age']
    >>> list_2 = ['wang', 23]
    >>> zip(list_1, list_2)
    [('name', 'wang'), ('age', 23)]
    >>> dict(zip(list_1, list_2))
    {'age': 23, 'name': 'wang'}
    

    如果两个参数不一样长,那么取短的。  

    也可以反向操作,见下面:

    >>> list_3
    {'age': 23, 'name': 'wang'}
    >>> list_1 = ['name', 'age']
    >>> list_2 = ['wang', 23]
    >>> list_3 = zip(list_1, list_2)
    >>> list_3
    [('name', 'wang'), ('age', 23)]
    >>> l1, l2 = zip(*list_3)
    >>> list_1 == list(l1)
    True
    >>> type(l1)
    <type 'tuple'>
    >>> list_2 == l2
    False
    >>> list_2 == list(l2)
    True
    

     

     自然,也可以操作三个或者一个参数:

    >>> zip(list_1)
    [('name',), ('age',)]
    >>> zip(list_1, list_2, l1)
    [('name', 'wang', 'name'), ('age', 23, 'age')]
    

      

    python.org的解释:

    1. This function returns a list of tuples, where the i-th tuple contains the i-th element from each of the argument sequences or iterables. The returned list is truncated in length to the length of the shortest argument sequence. When there are multiple arguments which are all of the same length, zip() is similar to map() with an initial argument of None. With a single sequence argument, it returns a list of 1-tuples. With no arguments, it returns an empty list.

    2. 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).

    3.zip() in conjunction with the * operator can be used to unzip a list

  • 相关阅读:
    java 后台校验格式
    spring AOP 实现事务和主从读写分离
    【Day5】项目实战.CSDN热门文章爬取
    【Day5】3.反爬策略之模拟登录
    【Day5】2.反爬策略之代理IP
    【Day5】1.Request对象之Header伪装策略
    【Day4】5.Request对象之Http Post请求案例分析
    【Day4】4.Request对象之Get请求与URL编码
    【Day4】3.urllib模块使用案例
    【Day4】2.详解Http请求协议
  • 原文地址:https://www.cnblogs.com/wswang/p/5555716.html
Copyright © 2011-2022 走看看