python - 如何将函数应用于数据框列

Question

races = pd.read_csv("C:/Users/Sam/Documents/races.csv")
df_races = pd.DataFrame(races)
df_races = df_races[["raceId", "year", "name"]]
df_races = df_races.sort_values(by=['year'])
df_races = df_races[df_races['name'] == 'Australian Grand Prix']
# Australian Grand Prix 'Find Qualifying Data'
QLF = pd.read_csv("C:/Users/Sam/Documents/qualifying.csv")
df_QLF = pd.DataFrame(QLF)
df_QLF = df_QLF[["raceId", "position", "q1", "q2", "q3"]]
Race_Id_1 = df_races['raceId'].tolist()
# Filter Rows
df_QLF['Match'] = df_QLF["raceId"].isin(Race_Id_1)
def Find_Rid(row):
if row['Match'] == 'True':
    return row
df_QLF = df_QLF.apply(Find_Rid, axis=1)

print(df_QLF)

一旦我运行了这一切，我就会得到以下输出，而实际上我想要的是当 df_QLF['Match'] column == 'True' 时保留这些行并丢弃所有其他行

   0         None
   1         None
   2         None
   3         None
   ....      ....

我不明白为什么。

Answer 1

df_QLF = df_QLF.loc[df_QLF['Match'] == True]