How to add a suffix (or prefix) to each column name?

I want to add _x suffix to each column name like so:

    featuresA = myPandasDataFrame.columns.values + '_x'

How do I do this? Additionally, if I wanted to add x_ as a suffix, how would the solution change?

You can use a list comprehension:

    df.columns = [str(col) + '_x' for col in df.columns]

There are also built-in methods like .add_suffix() and .add_prefix() as mentioned in another answer.