How do you add a simple counter column that increases by one in each row to a Pandas DataFrame?

Question

I have been running into this problem a lot. If you have an existing DataFrame in Pandas, and you want to add a row that is simply an increasing count, ie. 0, 1, 2..., what is the most efficient way to do it?

Thanks!

Sam

Answer 1

The easiest way might be

df = df.reset_index()

This will give you a new index starting at 0.

You could also do

df['counter'] = range(len(df))