Hi there,
give this a try and let me know how if you have questions.
#!/usr/local/bin/perl
use 5.016; #version >=5.12 turns on strictures by default
use warnings;
use autodie qw/ open close /; #saves typing die all the time
die "Usage: $0 infile1 infile2\n" unless @ARGV == 2;
my %count_cols;
my @cols;
while( <> ) { # perl will read/process one file in whole then move o
+n to the next
chomp;
# get 1st col from each line using an array slice
push @cols, ( split( /\t/, $_ ) )[0];
}
for ( @cols ) {
$count_cols{ $_ }++; # hash value = how many times does col name a
+ppear
}
my @intersects; # store columns that appear in both files
for ( keys %count_cols ) {
if( $count_cols{ $_ } == 2 ) {
push @intersects, $_;
}
}
# open fileA again and extract fields in second column
open IN, "<", "fileA";
while( my $line = <IN> ) {
chomp $line;
next if ! $line;
for my $intersect ( @intersects ) {
if( $intersect eq ( split( /\t/, $line ) )[0] ) {
my $result = ( split( /\t/, $line ) )[1];
say $result; # prints with \n, supported in >5.10
}
}
}
close IN;