The issue discussed here is occurring for me in 0.18.1: The columns optional argument of to_csv is being ignored.
Comment From: jreback
you will have to show a self contained example and pd.show_versions() as that issue was fixed 3 yrs ago
Comment From: jonathanlandy
Sorry, my mistake -- I was using "cols" as the argument not "columns". It is indeed working with the latter.