您只需要apply在groupby对象上使用。我修改了示例数据，使其更加清晰：
import pandas
from io import StringIO
csv = StringIO("""index,A,B
0,1,0.0
1,1,3.0
2,1,6.0
3,2,0.0
4,2,5.0
5,2,7.0""")
df = pandas.read_csv(csv, index_col='index')
groups = df.groupby(by=['A'])
print(groups.apply(lambda g: g[g['B'] == g['B'].max()]))
哪些打印：
A B
A index
1 2 1 6
2 4 2 7
602392714
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