Python Pandas GroupBy function

Author: Al-mamun Sarkar Date: 2020-04-01 17:24:28

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