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

This warning message occurs in pandas when you try to modify a subset of a DataFrame that is actually a copy of the original DataFrame, rather than a view. This can lead to unexpected results and is generally not recommended.

To avoid this warning and ensure that you are modifying the original DataFrame, you can use the .loc or .iloc accessor to select the subset of data you want to modify. For example:

df.loc[df['column'] == 'value', 'new_column'] = 'new_value'

This will modify the original DataFrame rather than creating a copy