modify pandas column value based on another column

Asked Dec 13 '18 at 01:26

Active Dec 13 '18 at 01:28

Viewed 28 times

Here is my dataframe:

                      Nets  y_start  draw_length color bar_label  label_pos
2018-07-30 06:04:10  11319      0.0      11319.0  grey    11,319      11319
2018-08-20 08:11:45  21889  11319.0      10570.0  grey    21,889      21889
2018-09-10 08:39:19  16270  21889.0      -5619.0   red    16,270      16270

I need to subtract 10000 from the existing lable_pos if the color is red.

I tried this but I get invalid syntax-

df['label_pos'] = df['lable_pos'] - 10000 if df['color'].isin('red')

what I'm after is the last row in this example is:

2018-09-10 08:39:19  16270  21889.0      -5619.0   red    16,270      15270

edited Dec 13 '18 at 01:28

asked Dec 13 '18 at 01:26

Timothy Lombard

1

`df['label_pos'] = np.where(df['color'] == 'red', df['label_pos']-1000,df['label_pos'])` – cs95 Dec 13 '18 at 01:28
`np.select(df['color']=='red', (df['label_pos'] - 10000), df['label_pos'])` – It_is_Chris Dec 13 '18 at 01:31
@coldspeed thanks. I missed the numpy callout in https://stackoverflow.com/questions/21608228/conditional-replace-pandas – Timothy Lombard Dec 13 '18 at 01:33

modify pandas column value based on another column

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