This is the challenge:
The file contains "pairs" of lines (2D-2D measurements on two lines).
Most -correct- measurements are on one line (column 3, 7, 8 and 9 are unique).
If there is a "match" on column 3, 7, 8 and 9 (name, date, time, machine),
then replace the two lines by one line.
(Print Column 1,2,3... 21, 22, 23 and the modified 10,11,12).
Column 10, 11 (first line) are "Vertical" and "Length".
Column 11, 12 (second line) are "Length" and "Lateral".
I want to "average" the length values of column 11.
What's a good approach? (any comparable examples on Perlmonks?)
The text file contains about 10.000 lines and I don't prefer an (VBA) Excel solution.

In reply to Combining matching lines in a TAB seperated textfile by Wobbel

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