Hi guys, I am a complete perl novice so forgive me in advance. I have been searching the web and haven't been able to find a solution. I have a really big text file called "HGDP.txt" that looks like this:

1 51 Brahui A C A A T

1 51 Brahui A C A G T

3 51 Brahui A C A G C

3 51 Brahui A C G A T

5 51 Brahui A C G A T

5 51 Brahui A C G G C

7 51 Brahui A C G A T

7 51 Brahui A C G G T

9 51 Brahui A C G G T

9 51 Brahui A C G G T

Except that the total number of columns are 2,841. I want to use perl to generate another output file whereby if the first column is of equal value (i.e. duplicates of 1, 3, 5...etc.) then I want to merge the two lines together with a "/" character as a delimiter. For example:

1 51 Brahui A/A C/C A/A A/G T/T

3 51 Brahui A/A C/C A/G G/A C/T

Is there a way to do that?

In reply to How to match duplicate lines in a text file and extract only one of those lines to a new file by danica

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