SettingWithCopyWarning:A value is trying to be set on a copy of a slice from a DataFrame.

• 问题描述

  df['new_column'] = df['old_column']

  上述命令导致如题问题。

• 解决方案

  涉及Python底层数据处理，关键字： __getitem__ 、 chained indexing 。

  简单来讲的话，尽量用df.loc[行名, 列名] = 值方式赋值，不采用df[][]方式赋值。

• Reference

1. Pandas - A value is trying to be set on a copy of a slice from a DataFrame