Python groupby,聚合，分组级运算

# -*- coding: UTF-8 -*-import pandas as pdimport numpy as npdf = pd.DataFrame({'key1':list('aabba'),                  'key2': ['one','two','one','two','one'],                  'data1': np.random.randn(5),                  'data2': np.random.randn(5)})print df['data1'].groupby(df['key1']).mean()print df.groupby(['key1','key2'])['data2'].mean()print df.groupby(['key1','key2'])[['data2']].mean()

C:\Python27\python.exe C:/Users/卢沛公/PycharmProjects/data_processing/AATEST2.pykey1a    0.255057b    0.267992Name: data1, dtype: float64key1  key2a     one    -0.803073      two    -0.295868b     one     1.038891      two    -1.231767Name: data2, dtype: float64              data2key1 key2          a    one  -0.803073     two  -0.295868b    one   1.038891     two  -1.231767