Using awk to switch columns

bioinformatics_guy · 10-30-2008, 08:09 AM

I have a file of the following form:

001 002
001 003
001 004
001 003
002 001
002 004
002 004
002 005
... ...

Which has already been sorted once. However, the column position is trivial as in 001 002 is the same as 002 001, so what I want to do is go down each line and if the number in the second column is smaller than the number in the first column, I want them to switch positions. Is this possible?

H_TeXMeX_H · 10-30-2008, 08:25 AM

Sure:

Code:

awk '{ if($2 < $1){print $2" "$1} else {print $1" "$2} }' testing.txt

Code:

bioinformatics_guy · 10-30-2008, 08:52 AM

TeXMeX,

You beat me to the punch, I was just about to post the EXACT same code, but I had a semicolon before the else -- which I thought you needed? Does it not matter?

H_TeXMeX_H · 10-30-2008, 09:50 AM

No, there should not be a semicolon before the else. It's just a C-style if-else statement. Remember to use the '>' to output the result to a file.