仅当列中存在某些条件值时才进行分组

Question

我有个df

Key1  Key2   Condition  Score
K11   K21     100        1000
K11   K21     200        3000
K11   K21     100        2000
K12   K22     100        12
K12   K22     200        133
K12   K22     100        300
K14   K24     100        144
K14   K24     200        122
K14   K24     100        4000

只有在条件为100时，我才想对键列Key1和Key2 执行groupby，并找到分数的最大值。

 df_trial=(df['Condition']=='100').groupby(['Key1','Key2'], as_index=False).max('Score')

这段代码似乎不起作用，并且会产生错误。如何实现所需的输出？

预期产出

Key1  Key2   Condition  max_Score
K11   K21     100        2000
K12   K22     100        300
K14   K24     100        4000

Answer 1

这应该能行

import numpy as np
import pandas as pd


df = pd.DataFrame({'Key1': ['K11', 'K11', 'K11', 'K12', 'K12', 'K12', 'K14', 'K14', 'K14'],
          'Key2': ['K21', 'K21', 'K21', 'K22', 'K22', 'K22', 'K24', 'K24', 'K24'],
          'Condition': [100, 200, 100, 100, 200, 100, 100, 200, 100],
          'Score': [1000, 3000, 2000, 12, 133, 300, 144, 122, 4000]})

cond = df['Condition']==100
df_out = df.loc[cond].groupby(["Key1", "Key2"])['Score'].max().reset_index()
print(df_out)



   Key1 Key2  Score
0  K11  K21   2000
1  K12  K22    300
2  K14  K24   4000