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)

一旦我运行这一切，我得到以下输出，实际上我想要的是当 df_QLF['Match'] column == 'True' 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]

Answer 2

以下代码对我有用。 在 python 中， True和False是专门为 bool 类保留的常量。 参考：1) https://docs.python.org/2.3/whatsnew/section-bool.html 2) https://www.geeksforgeeks.org/bool-in-python/

def Find_Rid(row):
    if row['Match'] == True:
         return row
df_QLF_true = df_QLF.apply(Find_Rid, axis=1)
print(df_QLF_true)