如何根據其他 dataframe 的條件刪除 pandas 組

Question

我有兩個數據框，看起來像這樣

df1 =
   name   color
0  John   Blue
1  John   Red
2  Lucy   Green
3  Lucy   Blue
4  Max    Blue
2  Max    White

和

df2 =
   name   value
0  John   15
1  Lucy   20
2  Max    5

我試圖刪除df1中df2中的value低於 10的所有分組名稱（在這種情況下，我想刪除df1['name']='Max'所有行）。

我想要得到的結果是：

df1 =
   name   color
0  John   Blue
1  John   Red
2  Lucy   Green
3  Lucy   Blue

謝謝！

Answer 1

像這樣：

In [731]: res = pd.merge(df1, df2, on='name')
In [736]: res[res['value'].ge(10)][['name','color']]

Out[736]: 
   name  color
0  John   Blue
1  John    Red
2  Lucy  Green
3  Lucy   Blue

Answer 2

#get names that are greater than or equal to 10
filtr = df2.loc[df2.value.ge(10),'name']

#extract names that match filtr

df1.loc[df1.name.isin(filtr)]

    name    color
0   John    Blue
1   John    Red
2   Lucy    Green
3   Lucy    Blue

Answer 3

df1['name'].isin(['Max']) # select the df1 which name is 'Max'

df1=df1[~df1['name'].isin(['Max'])] # reverse select the other elements.