awk - need help comparing 2 files

[akhattri]

My question is related to another previous thread (http://ubuntuforums.org/showthread.php?t=1520823) . I am having a similar situation. What I need is if col1 & 2 of file 1 matches col 1 & 2 of file 2, print that line of file 2.

File 1:
a 1 A
a 2 T
a 3 C


File 2:
a 2 Y
a 3 R
a 4 Q
b 5 R


output:
a 4 Q
b 5 R

[tgalati4]

Could it be as simple as:



awk '
NR==FNR {
a[$1" "$2]=$3
}
NR>FNR {
k=$2" "$1;
if (k in a)
print k,a[k];
else
print $0
}
' file2 file1

[steeldriver]

:confused: The output you've shown seems to be the complement of what your description says

Another option might be to use grep -f, after cutting the 3rd column from file1, i.e.



$ grep -vf <(cut -d' ' -f-2 file1) file2
a 4 Q
b 5 R




$ grep -f <(cut -d' ' -f-2 file1) file2
a 2 Y
a 3 R




$ awk 'NR==FNR {a[$1" "$2]=$3; next} !a[$1" "$2] {print}' file1 file2
a 4 Q
b 5 R




$ awk 'NR==FNR {a[$1" "$2]=$3; next} a[$1" "$2] {print}' file1 file2
a 2 Y
a 3 R

[drmrgd]

Edit: Nevermind....got a bug. Gotta work on this for a minute more. Besides, Steeldriver's example is much, much better anyway!

Edit: OK, bug fixed. Had to take another approach, although I can't quite figure out why. Steeldriver's solution is still a little better as it's a little less work. But, since I had a personal vendetta against this problem, here's my solution anyway:



#!/usr/bin/perl


use warnings;
use strict;


my $file1 = shift;
open( my $fh1, "<", $file1 ) || die "Can't open '$file1' for reading: $!";
chomp( my @data1 = <$fh1> );
close( $fh1 );


my $file2 = shift;
open( my $fh2, "<", $file2 ) || die "Can't open '$file2' for reading: $!";
chomp( my @data2 = <$fh2> );
close( $fh2 );


my @results;
for ( @data2 ) {
my ($match) = $_ =~ /^(\w\s+\d)/;
if ( grep { /$match/ } @data1 ) {
print "$_\n";
}
}


Assuming the data size is small, it's easy enough to load them up into two arrays and then compare. My output is:



$ perl compare.pl file1.txt file2.txt
a 2 Y
a 3 R