代码在不需要时自动实现变量 [英] Code actualising automatically variables when not desired

问题描述

我已经隔离了较大代码的以下部分:

I have isolated the following part of a bigger code:

import numpy as np

population= np.random.normal(0,1,5)
individuals=population

print(population)

for i in range(len(individuals)):
    individuals[i]=0

print(population)

响应:

[-0.1791731  -0.0756427   0.44463943 -0.51173395  0.9121922 ]
[0. 0. 0. 0. 0.]

我不明白为什么结果不一样.

I can't understand why the results are not identical.

推荐答案

如果要复制numpy数组的内容，请使用.copy()，此刻正在执行的操作是将指针复制到列表. 因此，两个变量都指向相同的数据，因此，如果一个更改，它们都将更改.

use .copy() if you want to copy the content of the numpy array, what you are doing at the moment, is copying a pointer to the list. So both variables point to the same data, so if one changes they both change.

import numpy as np

population= np.random.normal(0,1,5)
individuals=population.copy()

print(population)

for i in range(len(individuals)):
    individuals[i]=0

print(population)

对于非数字列表，您可以使用[:]例如

For non-numpy lists you can use [:] eg

a = [1,2,3]
b = a[:]

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