Python Pandas GroupBy function

Python Pandas GroupBy function. The following shows how to use groupBy function of DataFrame using pandas module.

 

In [1]:

import pandas as pd

 

In [2]:

d = {'one':[1,1,1,1,1],
     'two':[2,2,2,2,2],
     'letter':['a','a','b','b','c']}

df = pd.DataFrame(d)
df

Out[2]:

	one	two	letter
0	1	2	a
1	1	2	a
2	1	2	b
3	1	2	b
4	1	2	c

 

In [3]:

one = df.groupby('letter')
one.sum()

Out[3]:

	one	two
letter
a	2	4
b	2	4
c	1	2

 

In [4]:

letterone = df.groupby(['letter', 'one']).sum()
letterone

Out[4]:

		two
letter	one
a	1	4
b	1	4
c	1	2

 

In [5]:

letterone.index

Out[5]:

MultiIndex(levels=[['a', 'b', 'c'], [1]],
           labels=[[0, 1, 2], [0, 0, 0]],
           names=['letter', 'one'])

 

In [6]:

letterone = df.groupby(['letter', 'one'], as_index=False).sum()
letterone

Out[6]:

	letter	one	two
0	a	1	4
1	b	1	4
2	c	1	2

 

In [7]:

letterone.index

Out[7]:

Int64Index([0, 1, 2], dtype='int64')

 

In [8]:

letterone['one'][2]

Out[8]:

1