How to conditionally update DataFrame column in Pandas

pandas, python

Solution

df.loc[df['line_race'] == 0, 'rating'] = 0

Problem

With this DataFrame, how can I conditionally set `rating` to 0 when `line_race` is equal to zero? ``` line_track line_race rating foreign 25 MTH 10 84 False 26 MTH 6 88 False 27 TAM 5 87 False 28 GP 2 86 False 29 GP 7 59 False 30 LCH 0 103 True 31 LEO 0 125 True 32 YOR 0 126 True 33 ASC 0 124 True ``` In other words, what is the proper way on a DataFrame to say if ColumnA = x then ColumnB = y else ColumnB = ColumnB

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