python code to check columns with empty values code example

Example 1: python if column is null then

df['real_lastName'] = np.where(df['LastName'].isnull(), df['Middle'], df['LastName'] )

print (df)
  FirstName Middle LastName real_lastName
0       Tom     Ju      NaN            Ju
1      Kity    NaN      Rob           Rob

Example 2: python find cells with na

In [152]: import numpy as np
In [153]: import pandas as pd
# to return the row and column indices where the value in NaN
In [154]: np.where(pd.isnull(df))
Out[154]: (array([2, 5, 6, 6, 7, 7]), array([7, 7, 6, 7, 6, 7]))

In [155]: df.iloc[2,7]
Out[155]: nan

In [160]: [df.iloc[i,j] for i,j in zip(*np.where(pd.isnull(df)))]
Out[160]: [nan, nan, nan, nan, nan, nan]