关于python：列表复制不工作？


List copy not working?

本问题已经有最佳答案，请猛点这里访问。

我有一些关于Python的东西，我无法理解。我有一个列表，叫做数据：

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data = [[75], [95, 64], [17, 47, 82], [18, 35, 87, 10], [20, 4, 82, 47, 65], [19, 1, 23, 75, 3, 34], [88, 2, 77, 73, 7, 63, 67], [99, 65, 4, 28, 6, 16, 70, 92], [41, 41, 26, 56, 83, 40, 80, 70, 33], [41, 48, 72, 33, 47, 32, 37, 16, 94, 29], [53, 71, 44, 65, 25, 43, 91, 52, 97, 51, 14], [70, 11, 33, 28, 77, 73, 17, 78, 39, 68, 17, 57], [91, 71, 52, 38, 17, 14, 91, 43, 58, 50, 27, 29, 48], [63, 66, 4, 68, 89, 53, 67, 30, 73, 16, 69, 87, 40, 31], [4, 62, 98, 27, 23, 9, 70, 98, 73, 93, 38, 53, 60, 4, 23]]

我想创建一个数据副本，它的数据将被反转(1变为99，依此类推)。

然后我得到排序后的值和反向的值：

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sorted_vals = [1, 2, 3, 4, 6, 7, 9, 10, 11, 14, 16, 17, 18, 19, 20, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 43, 44, 47, 48, 50, 51, 52, 53, 56, 57, 58, 60, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 77, 78, 80, 82, 83, 87, 88, 89, 91, 92, 93, 94, 95, 97, 98, 99]
reverse_vals = [99, 98, 97, 95, 94, 93, 92, 91, 89, 88, 87, 83, 82, 80, 78, 77, 75, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 60, 58, 57, 56, 53, 52, 51, 50, 48, 47, 44, 43, 41, 40, 39, 38, 37, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 23, 20, 19, 18, 17, 16, 14, 11, 10, 9, 7, 6, 4, 3, 2, 1]

我创建数据的副本：

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rev_data = data[:]

然后，我在浏览列表时更改数据：

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for index, item in enumerate(rev_data):
    for s_index, s_item in enumerate(item):
        rev_data[index][s_index] = reverse_val[sort_val.index(s_item)]

我的问题是，无论我创建rev_数据的方法是什么，在这个过程中数据也会被修改！

我试过：

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rev_data = list(data)
rev_data = data[:]

rev_data = []
rev_data.extend(data)

每次，最终的答案都是正确的，但数据也会改变。…

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data = [[25], [4, 35], [83, 52, 18], [82, 64, 16, 91], [78, 95, 18, 52, 34], [80, 99, 77, 25, 97, 65], [14, 98, 23, 26, 93, 37, 32], [1, 34, 95, 71, 94, 87, 29, 9], [57, 57, 73, 43, 17, 58, 19, 29, 66], [57, 51, 27, 66, 52, 67, 63, 87, 6, 70], [44, 28, 53, 34, 75, 56, 10, 47, 3, 48, 88], [29, 89, 66, 71, 23, 26, 83, 20, 60, 31, 83, 41], [10, 28, 47, 62, 83, 88, 10, 56, 40, 50, 72, 70, 51], [37, 33, 95, 31, 11, 44, 32, 69, 26, 87, 30, 16, 58, 68], [95, 38, 2, 72, 77, 92, 29, 2, 26, 7, 62, 44, 39, 95, 77]]
相关讨论

data[:]创建了清单data的浅拷贝。由于这是一个列表列表，而且您还希望复制内部列表，因此需要一个深度复制：

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rev_data = copy.deepcopy(data)

或

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rev_data = [x[:] for x in data]
相关讨论

使用copy.deepcopy复制嵌套的可变对象。

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import copy
rev_data = copy.deepcopy(data)
..................... 

即：

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>>> import copy
>>> data = [[75], [95, 64], [17, 47, 82], [18, 35, 87, 10], [20, 4, 82, 47, 65], [19, 1, 23, 75, 3, 34], [88, 2, 77, 73, 7, 63, 67], [99, 65, 4, 28, 6, 16, 70, 92], [41, 41, 26, 56, 83, 40, 80, 70, 33], [41, 48, 72, 33, 47, 32, 37, 16, 94, 29], [53, 71, 44, 65, 25, 43, 91, 52, 97, 51, 14], [70, 11, 33, 28, 77, 73, 17, 78, 39, 68, 17, 57], [91, 71, 52, 38, 17, 14, 91, 43, 58, 50, 27, 29, 48], [63, 66, 4, 68, 89, 53, 67, 30, 73, 16, 69, 87, 40, 31], [4, 62, 98, 27, 23, 9, 70, 98, 73, 93, 38, 53, 60, 4, 23]]
>>> reverse_vals = [99, 98, 97, 95, 94, 93, 92, 91, 89, 88, 87, 83, 82, 80, 78, 77, 75, 73, 72, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 60, 58, 57, 56, 53, 52, 51, 50, 48, 47, 44, 43, 41, 40, 39, 38, 37, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 23, 20, 19, 18, 17, 16, 14, 11, 10, 9, 7, 6, 4, 3, 2, 1]
>>> sorted_vals = [1, 2, 3, 4, 6, 7, 9, 10, 11, 14, 16, 17, 18, 19, 20, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 43, 44, 47, 48, 50, 51, 52, 53, 56, 57, 58, 60, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 77, 78, 80, 82, 83, 87, 88, 89, 91, 92, 93, 94, 95, 97, 98, 99]
>>> for index, item in enumerate(rev_data):
...     for s_index, s_item in enumerate(item):
...         rev_data[index][s_index] = reverse_vals[sorted_vals.index(s_item)]
...        
>>> data
[[75], [95, 64], [17, 47, 82], [18, 35, 87, 10], [20, 4, 82, 47, 65], [19, 1, 23, 75, 3, 34], [88, 2, 77, 73, 7, 63, 67], [99, 65, 4, 28, 6, 16, 70, 92], [41, 41, 26, 56, 83, 40, 80, 70, 33], [41, 48, 72, 33, 47, 32, 37, 16, 94, 29], [53, 71, 44, 65, 25, 43, 91, 52, 97, 51, 14], [70, 11, 33, 28, 77, 73, 17, 78, 39, 68, 17, 57], [91, 71, 52, 38, 17, 14, 91, 43, 58, 50, 27, 29, 48], [63, 66, 4, 68, 89, 53, 67, 30, 73, 16, 69, 87, 40, 31], [4, 62, 98, 27, 23, 9, 70, 98, 73, 93, 38, 53, 60, 4, 23]]
>>> rev_data
[[25], [4, 35], [83, 52, 18], [82, 64, 16, 91], [78, 95, 18, 52, 34], [80, 99, 77, 25, 97, 65], [14, 98, 23, 26, 93, 37, 32], [1, 34, 95, 71, 94, 87, 29, 9], [57, 57, 73, 43, 17, 58, 19, 29, 66], [57, 51, 27, 66, 52, 67, 63, 87, 6, 70], [44, 28, 53, 34, 75, 56, 10, 47, 3, 48, 88], [29, 89, 66, 71, 23, 26, 83, 20, 60, 31, 83, 41], [10, 28, 47, 62, 83, 88, 10, 56, 40, 50, 72, 70, 51], [37, 33, 95, 31, 11, 44, 32, 69, 26, 87, 30, 16, 58, 68], [95, 38, 2, 72, 77, 92, 29, 2, 26, 7, 62, 44, 39, 95, 77]]

您有一个嵌套列表列表，因此需要复制两个级别的深度。

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data_copy = [inner_list[:] for inner_list in data]

reverse_data = reversed(data)

reverse_data将是一个迭代器。您可以遍历它，也可以使用list(reverse_data)将它强制到一个列表中。

关于内置函数的更多信息：http://docs.python.org/library/functions.html revered-把它放在枕头下面。

编辑：如果只想从100中减去值列表：

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from operator import sub
from functools import partial
subtract_map = partial(map, partial(sub,100)) # this is more convenient than a nested list comprehension
complements = [subtract_map(l) for l in data]
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