Re: Is there any efficient way i can take out a specific column from hundreds of files and put it in one file?

[CountZero]

It needs a few lines of Perl code only:

use Modern::Perl qw/2014/;
use File::Find::Iterator;

my $find =
  File::Find::Iterator->create( dir => ['d:/Perl/scripts'], filter => 
+\&find );
open my $FH_OUT, '>', './results.CSV' or die "Could not open results f
+ile - $!";
while ( my $file = $find->next ) {
    open my $FH_IN, '<', $file or die "Could not open $file - $!";
    say $FH_OUT join ', ', ( split /,/ )[ 0, 2 ] while (<$FH_IN>);
}

sub find { /GENES\d+\.csv/; }

I tested it with 1000 files of 1000 lines of 10 fields each: Extracting the first and third column and saving them in the results file took 47 seconds on my ASUS tablet with a 1.33 GHz Intel ATOM Z3740 (4 core) processor. I call that very efficient.