python - How to check if a column exists in Pandas

Question

Is there a way to check if a column exists in a Pandas DataFrame?

Suppose that I have the following DataFrame:

>>> import pandas as pd
>>> from random import randint
>>> df = pd.DataFrame({'A': [randint(1, 9) for x in xrange(10)],
                       'B': [randint(1, 9)*10 for x in xrange(10)],
                       'C': [randint(1, 9)*100 for x in xrange(10)]})
>>> df
   A   B    C
0  3  40  100
1  6  30  200
2  7  70  800
3  3  50  200
4  7  50  400
5  4  10  400
6  3  70  500
7  8  30  200
8  3  40  800
9  6  60  200

and I want to calculate df['sum'] = df['A'] + df['C']

But first I want to check if df['A'] exists, and if not, I want to calculate df['sum'] = df['B'] + df['C'] instead.

Answer 1

This will work:

if 'A' in df:

But for clarity, I'd probably write it as:

if 'A' in df.columns: