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
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Answer 1

To check if one or more columns all exist, you can use set.issubset, as in:

if set(['A','C']).issubset(df.columns):
   df['sum'] = df['A'] + df['C']                

As @brianpck points out in a comment, set([]) can alternatively be constructed with curly braces,

if {'A', 'C'}.issubset(df.columns):

See this question for a discussion of the curly-braces syntax.

Or, you can use a list comprehension, as in:

if all([item in df.columns for item in ['A','C']]):

Answer 2

Just to suggest another way without using if statements, you can use the get() method for DataFrames. For performing the sum based on the question:

df['sum'] = df.get('A', df['B']) + df['C']

The DataFrame get method has similar behavior as python dictionaries.

Answer 3

This will work:

if 'A' in df:

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

if 'A' in df.columns: