技术

Python 奇技淫巧

  • 数组降维

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    matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
    [k for i in matrix for k in i]
    >>> [1, 2, 3, 4, 5, 6, 7, 8, 9]

  • 矩阵行列互转

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    a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
    re_a = list(zip(*a))
    >>> [[1, 4, 7], [2, 5, 8], [3, 6, 9]]

  • 字典的键、值互换

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    a = {'a': 1, 'b': 2, 'c': 3, 'd': 4}
    def reverse_dict(a):
        k = a.keys()
        v = a.values()
        new_dict = dict(zip(v, k))
        return new_dict

  • 合并一个list的相邻项

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    a = [1, 2, 3, 4, 5, 6]
    list(zip( a[::2], a[1::2] ))
    >>> [(1, 2), (3, 4), (5, 6)]

  • 反转字符串

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    a = 'python'
    a[::-1]
    >>> 'nohtyp'

  • 统计list中1的个数

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a = [0, 1, 0, 0, 1, 0, 1, 0]
[i[0] for i in enumerate(a) if i[1] != 0]
>>>[1, 4, 6]

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