Remove Columns in Nifi

Question

I'm trying to remove the last 16 of 18 columns from a Flowfile with CSV-formatted text. I thought my regex pattern would work, but the output is the exact same as the original data. My log doesn't show anything because it thinks it applied the rule correctly, so something must be wrong with my regex. I've included two images below of my flow and the ReplaceText Processor attributes I have set.

Answer 1

Figured it out: I'm not sure if it was my grouping pattern not working or what, but I changed the .* to [,]* and made two separate groups for each of the first two columns, then a group of (.*) for the rest of the columns

^((?:[^,]*,))((?:[^,]*))((.*))