理解就地=真 [英] Understanding inplace=True

问题描述

在pandas 库中多次有一个选项可以就地更改对象，例如使用以下语句...

In the pandas library many times there is an option to change the object inplace such as with the following statement...

df.dropna(axis='index', how='all', inplace=True)

我很好奇返回的内容以及在传递 inplace=True 时与传递 inplace=False 时对象的处理方式.

I am curious what is being returned as well as how the object is handled when inplace=True is passed vs. when inplace=False.

当inplace=True 时，是否所有操作都修改了self?当 inplace=False 是一个立即创建的新对象时，例如 new_df = self 然后返回 new_df ?

Are all operations modifying self when inplace=True? And when inplace=False is a new object created immediately such as new_df = self and then new_df is returned?

推荐答案

当 inplace=True 被传递时，数据就地重命名(它什么都不返回)，所以你会使用:

When inplace=True is passed, the data is renamed in place (it returns nothing), so you'd use:

df.an_operation(inplace=True)

当 inplace=False 被传递时(这是默认值，所以不是必需的)，执行操作并返回对象的副本，所以你会使用:

When inplace=False is passed (this is the default value, so isn't necessary), performs the operation and returns a copy of the object, so you'd use:

df = df.an_operation(inplace=False) 

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