Thanks for everybody's great suggestions. Just to clear things up, there are no overlap between the groups. Each 2-digit combination can only appear in one group. Although, not every 2-digit combo will be represented. It would be helpful to handle these rogue entries.

The input file is currently around 5-6k lines.

In reply to Re: Efficient Grouping by meetraz
in thread Efficient Grouping by meetraz

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