在Python中初始化2D数组 [英] Initializing 2D array in Python

问题描述

我在python中初始化2D数组时遇到问题.我想要一个6x6的阵列，我做到了

I have a problem with initialzing a 2D array in python. I want a 6x6 array, I did

arr = [[None]*6]*6

但是当我这样做时:

>>> arr[1][2]=10
>>> arr
[[None, None, 10, None, None, None], [None, None, 10, None, None, None], [None, None, 10, None, None, None], [None, None, 10, None, None, None], [None, None, 10, None, None, None], [None, None, 10, None, None, None]]

注意，我只设置了1个项目，并且在所有行上都将其复制"了.怎么了?我认为它与引用相同的列表有关，但是我该如何解决呢?

Notice I just set 1 item, and its "replicated" on all rows. Whats wrong? I think it has to do with its referencing the same list, but how do I fix this?

我想通了

for key, _ in algos.items():
    algoData[key] = []
    for i in range(0,6):
        algoData[key].append([])
        for j in range(0,6):
            algoData[key][i].append(None)

可以工作，但是只是初始化一个空的6x6数组似乎很长，如果我想要10000x10000数组怎么办，效率会很低?

works, but it seems long to just initialize an empty 6x6 array, what if I want a 10000x10000 array, it will be very inefficient?

更新

我还可以初始化2D数组的字典吗?我有一本类似的字典:

Can I also initialize a dictionary of 2D arrays? I have a dictionary like:

algos = { "FIFO": ..., "LRU": ..., "Random": ... }

我想初始化一个字典，如下所示:

I want to initialize a dictionary like below:

algoData = { "FIFO": 2D arr, "LRU": 2D arr, "Random": 2D arr }

推荐答案

使用列表推导，您可以说:

Using list comprehensions, you can say:

arr = [[None for x in range(6)] for y in range(6)]

然后，您将按预期的方式运行arr[1][2] = 10.但是，这不是很正常的事情.您打算将嵌套列表用于什么?可能有更好的方法.例如，使用numpy包使处理数组变得更加容易.

Then you will have arr[1][2] = 10 working as expected. This is not a very normal thing to do, however. What are you going to use the nested lists for? There may be a better way. For example, working with arrays is made much easier with the numpy package.

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