python:对我的复制变量的更改会影响原始变量 [英] python: changes to my copy variable affect the original variable

问题描述

我有一个列表，我创建了一个副本，以便在保留原始列表的同时进行一些操作.但是，当我将 copy_list 设置为 org_list 时，它们变成了相同的东西，如果我更改 copy_list, org_list> 也有变化.例如:

I've got a list that I create a copy of in order to do some manipulations while still keeping the original list. However, when I set copy_list equal to org_list, they become the same thing, and if I change copy_list, org_list changes too. For example:

org_list = ['y', 'c', 'gdp', 'cap']

copy_list = org_list

copy_list.append('hum')

print(copy_list)
print(org_list)

返回

['y', 'c', 'gdp', 'cap', 'hum']
['y', 'c', 'gdp', 'cap', 'hum']

我不太了解实际发生的事情，但看起来 org_list 实际上是将自己传递给 copy_list 以便它们实际上是同一件事.

I don't know too much about what is actually going on but it looks like org_list is actually passing itself to copy_list so that they are actually the same thing.

有没有办法制作一个独立的 org_list 副本，而不用做一些笨拙的事情:

Is there a way to make an independent copy of org_list without doing something clumsy like:

copy_list = []
for i in org_list:
    copy_list.append(i)

我这么说是因为我对其他类型的变量也有同样的问题，例如熊猫数据框.

I say this because I have the same problem with other types of variables, for example a pandas dataframe.

推荐答案

那是因为在 python 设置变量中实际上设置了对变量的引用.几乎每个学习 Python 的人都会在某个时候遇到这个问题.解决方法很简单:复制列表:

That is because in python setting a variable actually sets a reference to the variable. Almost every person learning python encounters this at some point. The solution is simply to copy the list:

copy_list = org_list[:] 

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