How select rows with multiple conditions and calculate a new column in the original dataframe

Question

I need to use the following code:

raw_data.loc[(raw_data['PERMNO']==10006)&(raw_data['month']>=50)&(raw_data['month']<=100)]['resi']=raw_data['RET']-raw_data['ewretd']

that is based on the conditions to calculate column 'resi'.

But I keep getting warnings like

D:\Anaconda3\lib\site-packages\ipykernel_launcher.py:1: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy """Entry point for launching an IPython kernel.

How to correct this?

Did you read the documentation the warning message links you to? It's very thorough — camille, Sep 13 '21 at 12:56

U13-Forward · Accepted Answer · 2021-09-12T09:43:02.003

0

Try adding df.copy:

raw_data = raw_data.copy()
raw_data.loc[(raw_data['PERMNO']==10006)&(raw_data['month']>=50)&(raw_data['month']<=100), 'resi'] = raw_data['RET'] - raw_data['ewretd']

edited Sep 12 '21 at 09:43

answered Sep 12 '21 at 09:25

U13-Forward

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but I need to calculate in the same dataframe – Canvas Sep 12 '21 at 09:34
@Canvas Edited my answer, add this line before your code – U13-Forward Sep 12 '21 at 09:34
Still the same warning. Actually, there is no column 'resi' in the dataframe, should I insert the column first? – Canvas Sep 12 '21 at 09:42

How select rows with multiple conditions and calculate a new column in the original dataframe

1 Answers1