pandas check if column is null with query function

Question

I have pandas dataframe that I want to execute on it query function with isnull() or not isnull() condition like that:

In [67]: df_data = pd.DataFrame({\'a\':[1,         


        

Answer 1

Use .:

a = df_data.query('a.isnull()')
print (a)
    a
2 NaN

b = df_data.query('a.notnull()')
print (b)
      a
0   1.0
1  20.0
3  40.0
4  50.0

---

You can use also logic NaN != NaN:

a = df_data.query('a != a')
print (a)
    a
 2 NaN

b = df_data.query('a == a')
print (b)
      a
0   1.0
1  20.0
3  40.0
4  50.0