dataframe groupby_[pandas] groupby函數

大綱:

• df.groupby(col,sort=False)
• df.groupby(col)
• df.groupby(col).mean()

df.groupby(col)，傳回一個按列進行分組的groupby對象；

import 
           

import 
           

[

('2015-05-05', Date Sym Data2 Data3

3 2015-05-05 aapl 15 1

7 2015-05-05 aaww 40 120),

('2015-05-06', Date Sym Data2 Data3

2 2015-05-06 aapl 10 6

6 2015-05-06 aaww 100 60),

('2015-05-07', Date Sym Data2 Data3

1 2015-05-07 aapl 8 8

5 2015-05-07 aapl 60 100),

('2015-05-08', Date Sym Data2 Data3

0 2015-05-08 aapl 11 5

4 2015-05-08 aapl 110 50)

]

df.groupby(col,sort=False)

import pandas as pd

df2 = pd.DataFrame(
	{'Date': ['2015-05-08', '2015-05-07', '2015-05-06', '2015-05-05', '2015-05-08', '2015-05-07', '2015-05-06',
			  '2015-05-05'],
	 'Sym': ['aapl', 'aapl', 'aapl', 'aapl', 'aapl', 'aapl', 'aaww', 'aaww'],
	 'Data2': [11, 8, 10, 15, 110, 60, 100, 40],
	 'Data3': [5, 8, 6, 1, 50, 100, 60, 120]})




df11 = df2.groupby(df2['Date'],sort=False)

print(list(df11))
           

[

('2015-05-08', Date Sym Data2 Data3

0 2015-05-08 aapl 11 5

4 2015-05-08 aapl 110 50),

('2015-05-07', Date Sym Data2 Data3

1 2015-05-07 aapl 8 8

5 2015-05-07 aapl 60 100),

('2015-05-06', Date Sym Data2 Data3

2 2015-05-06 aapl 10 6

6 2015-05-06 aaww 100 60),

('2015-05-05', Date Sym Data2 Data3

3 2015-05-05 aapl 15 1

7 2015-05-05 aaww 40 120)]

df.groupby(col).mean()

df 
           

參考:

pandas groupby函數