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  • Python把同一个对象循环赋值给另外一个变量

    Python把同一个对象循环赋值给另外一个变量,修改一个对象,其他对象也修改了

    >>> row=['_'] * 3
    >>> board = []
    >>> for i in range(3):
    ...     board.append(row)
    ...
    >>> row
    ['_', '_', '_']
    >>> board
    [['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_']]
    >>> board[2][1]='A'
    >>> row
    ['_', 'A', '_']
    >>> board
    [['_', 'A', '_'], ['_', 'A', '_'], ['_', 'A', '_']]  #3个子对象都被修改了
    >>>

    如果不想复制对象,可以在循环赋值前初始化下被赋值的变量

    >>> board = []
    >>> for i in range(3):
    ...     row=['_'] * 3   #循环赋值前,初始化下变量
    ...     board.append(row)
    ...
    >>> board
    [['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_']]
    >>> row
    ['_', '_', '_']
    >>> board[2][0] = 'X'
    >>> board
    [['_', '_', '_'], ['_', '_', '_'], ['X', '_', '_']]
    >>> row
    ['X', '_', '_']
    >>>
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  • 原文地址:https://www.cnblogs.com/testway/p/8108730.html
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