How to speed up cell increment in Pandas DataFrame?

Question

I need to apply integer increment on a cell in a Pandas DataFrame. The code below works correctly. However, it is very slow in a loop:

df.at[index, column_name] += 2

Is there a way to speed it up?

Answer 1

It should be a lot simpler:

df[columns] += 2

Or, if you want to do it for every column:

df += 2

If you have a special selection of indexes to use, try this:

indexes = [0, 4, 5, 8]
columns = ['a', 'b', 'k']
df.loc[indexes, columns] += 2