getting columns of data from very large text files

[tester]

I'm thinking about this: www.openbci.com

If you go to downloads, and get this, inside there - there are some example data snapshots in txt files. From what I see, it's n-columns format (omma separated columns, 1st row can be removed, all columns are filled, so there are no nil cells), where each column represents single channel.

What I need is a sort of splitter, that extracts columns from such data text files and saves channels to separate text files.

Now the problem. I have a working solution (combination of greens and ruby) that performs well on relatively small text files (it's somewhere on the forum). But with large one (few MB or more) it seems to not work. First value is captured, and nothing else. I guess this is due to green-ruby combination (comma separation versus green nodes for text/string), and probably ruby goes down.

How to get it in flowstone's ruby?