I understand. I believe that using hash tables would speed things up significantly. I don't need sort of matches, because my data has been designed such that my list of names exactly match the corresponding entries within the table (i.e. regex).

The list of names looks like this:

1000567/1
1000567/2
1000574/1
1000574/2

And the total data (from which I want to extract the matching columns) looks like this:

I have removed the tabs and replaced them with commas, so that each entry is in one string
1083978/2,284224,284292,chrX,255,+,284224,284292,255,0,0,1,68,0
122854/1,284224,284277,chrX,255,+,284224,284277,255,0,0,1,53,0
641613/1,284224,284290,chrX,255,+,284224,284290,255,0,0,1,66,0


Separately, I have the first column as a matching "hash file"
1083978/2
122854/1
641613/1

So now, I will use the hash file and the comma-separated data to create hash and key pairs. I will put the hashes in a table. And finally, I will compared my hashes to my list of names using regex matching. For the hashes that match, I will fetch the keys and replace commas with tabs, thus giving me my original data. Does this seem sensible?

In reply to Re^2: Extacting lines where one column matches a name from a list of names by mr_clean
in thread Extacting lines where one column matches a name from a list of names by mr_clean

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