pandas -创建新列 [英] Pandas - Creating a New Column

问题描述

我总是使用以下命令在熊猫中添加新列:

I have always made new columns in pandas using the following:

df['new_column'] = value

我正在使用此方法，但是收到设置副本的警告.

I am using this method, however, am receiving the warning for setting a copy.

在不创建副本的情况下创建新列的方法是什么?

What is the way to make a new column without creating a copy?

推荐答案

尝试使用

df.loc[:,'new column'] = value

作为piRSquared注释，df可能是另一个DataFrame的副本，当您将值设置为df时，它可能会发生所谓的链式索引.有关更多信息，请参考 pandas文档 .

As piRSquared comments, dfis probably a copy of another DataFrame and when you set values to df it probably incurs in what is called chain indexing. Refer to pandas docs for further information.

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