python - How to conditionally update DataFrame column in Pandas -

with dataframe, how can conditionally set rating 0 when line_race equal 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, proper way on dataframe if columna = x columnb = y else columnb = columnb

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