The following code does what is required to be done however it keeps throwing an error => 'useless use of private variable in void context at line 21', this behavior showed up after I switched from using some disjointed if statements into a more compound given(){when(){}} construct. Frankly, I am at a total loss on how to resolve this, tried looking around for similar situations but the problem presentation was different and the replies just added to the confusion...

So fellow monks, I present before you the code after having become spent for my efforts with some records from the tab-delimited dataset, the combination of the code conditionals reflect whether or not some entries in the columns SNP, Allele1 and Allele2 are missing, and seeking your explanation on why this error arises and how to go about resolving it I afford you my appreciations and the kindest of gratitude .. 

#!/usr/local/bin/perl
use strict;
use warnings;
use Data::Dump qw(pp);
use feature qw(switch say);

my $path = "testSample.txt";
open(FH, $path) or die("error, $!\n");
my (%hetero, %homo, %unclassified);
until(eof(FH)){
       my ($file, $patientName, $panel, $snp, $allele1, $allele2, $siz
+e1, $size2)= split "\t", <FH>;
        $snp ||='';$allele1 ||= ''; $allele2||=''; #if not initialized
+ set to ''
        chomp($snp);
        $snp = 'missed' if $snp eq '';
        given($allele1, $allele2){
                when($allele1 ne '' && $allele2 ne ''){constructHetero
+($snp, $patientName, $allele1, $allele2)}
                when($allele1 ne '' && $allele2 eq ''){constructHomo('
+type1', $snp,$patientName, 'allele1', $allele1)}
                when($allele1 eq '' && $allele2 ne ''){constructHomo('
+type2', $snp,$patientName, 'allele2', $allele2)}
                when($allele1 eq '' && $allele2 eq ''){constructUnclas
+sified($snp, $patientName)}
                }
    }

sub constructHetero{
        my ($snp, $patientName, $allele1, $allele2) = @_;
        $hetero{$snp}{$patientName}{'allele1'}=$allele1;
        $hetero{$snp}{$patientName}{'allele2'}=$allele2;
        $hetero{$snp}{$patientName}{'records'}++;
        $hetero{$snp}{'total_records'}++;
        };

sub constructHomo{
        my ($type, $snp, $patientName, $alleleNumber,$allele)=@_;
        $homo{$type}{$snp}{$patientName}{$alleleNumber}=$allele;
        $homo{$type}{$snp}{$patientName}{'records'}++;
        $homo{$type}{$snp}{'total'}++;
        $homo{$type}{'total_records'}++;
        }
        
sub constructUnclassified{
        my($snp, $patientName)=@_;
        $unclassified{$snp}{$patientName}{'records'}++;
        $unclassified{$snp}{'total'}++;
        $unclassified{'total_records'}++;
        }

#print pp(\%hetero);
#print pp(\%homo);
#print pp(\%unclassified);

[download]
testSample.txt
Sample File    Sample Name    Panel    SNP    Allele 1    Allele 2    
+Size 1    Size 2
011.fsa    MS-039    Panel_3130
012.fsa    MS-039    Panel_3130                    31.76
014.fsa    MS-291    Panel_3130    rs7577363            90.79    92.46
013.fsa    MS-291    Panel_3130    rs7577363
006.fsa    MS-290    Panel_3130    rs10735781        G    78.69    80.
+31
005.fsa    MS-290    Panel_3130    rs10735781        G    78.85    80.
+32
011.fsa    MS-039    Panel_3130    rs10735781    C        78.63    80.
+1
001.fsa    MS-148    Panel_3130    rs10735781    C    G    78.57    80
+.2

[download]

Excellence is an Endeavor of Persistence. A Year-Old Monk :D .

In reply to Text Analysis: given(){when(){}} block throws a 'useless use of private variable...etc' error by biohisham

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