Python-更新一本字典中的值将更新所有字典中的值 [英] Python - Updating value in one dictionary is updating value in all dictionaries

问题描述

我有一个名为lod的词典列表.所有词典具有相同的键，但值不同.我正在尝试为所有词典中的同一键更新值列表中的一个特定值.

I have a list of dictionaries called lod. All dictionaries have the same keys but different values. I am trying to update one specific value in the list of values for the same key in all the dictionaries.

我正在尝试通过以下for循环来实现:

I am attempting to do it with the following for loop:

for i in range(len(lod)):
    a=lod[i][key][:]
    a[p]=a[p]+lov[i]
    lod[i][key]=a

发生的事情是每个字典正在更新len(lod)次，因此应该在lod[0][key][p]上添加lov[0]，但是要在其中添加lov[0]+lov[1]+.....

What's happening is each is each dictionary is getting updated len(lod) times so lod[0][key][p] is supposed to have lov[0] added to it but instead it is getting lov[0]+lov[1]+.... added to it.

我在做什么错了?

这是我声明字典列表的方式:

Here is how I declared the list of dicts:

lod = [{} for _ in range(len(dataul))]
for j in range(len(dataul)):
    for i in datakl:
        rrdict[str.split(i,',')[0]]=list(str.split(i,',')[1:len(str.split(i,','))])
    lod[j]=rrdict

推荐答案

问题出在如何创建词典列表.您可能做了这样的事情:

The problem is in how you created the list of dictionaries. You probably did something like this:

list_of_dicts = [{}] * 20

实际上是相同 dict 20次.尝试做这样的事情:

That's actually the same dict 20 times. Try doing something like this:

list_of_dicts = [{} for _ in range(20)]

没有看到您是如何实际创建的，这只是一个示例问题的示例解决方案.

Without seeing how you actually created it, this is only an example solution to an example problem.

要确定，请打印以下内容:

To know for sure, print this:

[id(x) for x in list_of_dicts]

如果在* 20方法中定义了它，则每个dict的id是相同的.在列表理解方法中，id是唯一的.

If you defined it in the * 20 method, the id is the same for each dict. In the list comprehension method, the id is unique.

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