在这里,你去过滤器
df.groupby('city').filter(lambda x : len(x)>3)
Out[1743]:
city
0 NYC
1 NYC
2 NYC
3 NYC
解决方案二 transform
sub_df = df[df.groupby('city').city.transform('count')>3].copy()
# add copy for future warning when you need to modify the sub df