如何在Pandas中有条件地更新DataFrame列

Question

使用此DataFrame,如何在等于零rating时有条件地设置为0 line_race？

    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

换句话说,DataFrame上的正确方法是说ColumnA = x然后ColumnB = y else ColumnB = ColumnB

Answer 1

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

Answer 2

使用numpy.where说if ColumnA = x then ColumnB = y else ColumnB = ColumnB：

df['rating'] = np.where(df['line_race']==0, 0, df['rating'])