Hi there PerlMonks, Here is my code: 
#!usr/bin/perl -w
use strict;

# open the file that has to be read
my $input = "Users/Dektop/file123.txt";
die "Cannot open $input\n" unless (open(IN, $input));

#open a new file which has to be made
open (my $out, ">outfile123.txt");

#In the while loop, put the columns that have to be printed in the new
+ file.
while(<IN>){
my @fields = split /\t/,$_;
    
    my $ID  = $fields[0];
    
        my $WEIGHTED_SUM = $fields[9];
    #print the columns     
    {
        print $out "$ID\ $WEIGHTED_SUM \n";
        }
        }
        
        #close the filehandles
close($input);
close($out);

[download]

The output file is extracting the ID column but for the WEIGHTED_SUM , I get the following error, Use of uninitialized value $WEIGHTED_SUM in concatenation (.) or string at sample1.pl line 20, <IN> line 2148788.

Can some tell me what is going on and why I am not able to extract both the columns? Is there a way to fix it?

In reply to Why is there only one column in the output file? by perllearner007

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