Pandas select only numeric or integer field from dataframe

Question

I have this Pandas dataframe (df):

     A    B
0    1    green
1    2    red
2    s    blue
3    3    yellow
4    b    black

A type is obje

Answer 1

You can use convert_objects, which when convert_numeric=True will forcefully set all non-numeric to nan. Dropping them and indexing gets your result.

This will be considerably faster that using apply on a larger frame as this is all implemented in cython.

In [30]: df[['A']].convert_objects(convert_numeric=True)
Out[30]: 
    A
0   1
1   2
2 NaN
3   3
4 NaN

In [31]: df[['A']].convert_objects(convert_numeric=True).dropna()
Out[31]: 
   A
0  1
1  2
3  3

In [32]: df[['A']].convert_objects(convert_numeric=True).dropna().index
Out[32]: Int64Index([0, 1, 3], dtype='int64')

In [33]: df.iloc[df[['A']].convert_objects(convert_numeric=True).dropna().index]
Out[33]: 
   A       B
0  1   green
1  2     red
3  3  yellow