6.29 - Pandas missing data

In [1]:

    

import numpy as np
import pandas as pd


    

In [2]:

    

d = {'a':[1,2,np.nan],'b':[5,np.nan,np.nan],'c':[1,2,3]}


    

In [4]:

    

df = pd.DataFrame(d)
df


    

    
Out[4]:






  

    

      

      
a
      
b
      
c
    
  
  

    

      
0
      
1.0
      
5.0
      
1
    
    

      
1
      
2.0
      
NaN
      
2
    
    

      
2
      
NaN
      
NaN
      
3
    
  

In [6]:

    

df.dropna() # drops all rows with missing values


    

    
Out[6]:






  

    

      

      
a
      
b
      
c
    
  
  

    

      
0
      
1.0
      
5.0
      
1
    
  

In [7]:

    

df.dropna(axis=1)


    

    
Out[7]:






  

    

      

      
c
    
  
  

    

      
0
      
1
    
    

      
1
      
2
    
    

      
2
      
3
    
  

In [8]:

    

df.fillna('WOOSH')


    

    
Out[8]:






  

    

      

      
a
      
b
      
c
    
  
  

    

      
0
      
1
      
5
      
1
    
    

      
1
      
2
      
WOOSH
      
2
    
    

      
2
      
WOOSH
      
WOOSH
      
3
    
  

In [11]:

    

df['a'].fillna(df['a'].mean())


    

    
Out[11]:





0    1.0
1    2.0
2    1.5
Name: a, dtype: float64

In [ ]: