I am attempting to write a piece of code that reads in a couple of files, takes the first two columns from a .tsv files as the Gene ID and Gene Symbol for a key/value pair in a hash, uses the second file to read in some data that corresponds to the Gene ID, and then prints the data to a new file. I am fairly new to programming and so of course am running into an uninitialized variable brick wall. I'm not sure if this is due to an improper array split, a logic issue with my RegEx or if it is one of those little brain farts. Anyways, any advice would be helpful! The uninitialized variable I'm running into is the first column of the array: "INF1Array[0]" on line 34. (Sorry if my formatting is a little unorthodox!)

    #!/usr/bin/perl
    use warnings;
    use diagnostics;
    
    # Title: convertDataToGeneSymbol.pl
    # Author: Nicholas Bense
    # Date: 11/4/15
    
    # Open a filehandle to read file #1
    open(INF1,"<",'/scratch/Drosophila/fb_synonym_fb_2014_05.tsv' ) or
+ die $!;
    
    # Open a filehandle to read file #2
    open(INF2,"<",'/scratch/Drosophila/FlyRNAi_data_baseline_vs_EGF.tx
+t') or die $!;
    
    # Open a filehandle to read file #3
    open(INF3,"<",'/scratch/Drosophila/gene_association.goa_fly') or d
+ie $!;
    
    # Open a filehandle to write new file
    open(OUTF1,">",'FLYRNAi_data_baseline_vs_EGFSymbol.txt') or die $!
+;
    
    # Initialize a hash for the gene symbol conversion
    my %geneSymbolConversion;
    
    # Read Input File 1 line by line
    while (<INF1>){
    
    # Get rid of whitespace
            chomp;
    
    # Split the line
            my @INF1Array = split("\t", $_);
    
    # Filter entries starting with FBgn
            while ($INF1Array[0] =~ /(^FBgn\d+)/){
    
    # Assign column 1 to hash key scalar
            my $geneID = $INF1Array[0];
    
    # Assign column 2 to hash value scalar
            my $geneSymbol = $INF1Array[1];
    
    # Assign key and value to hash
            $geneSymbolConversion{$geneID} = $geneSymbol;
    
    }
    
    }
    
    # Read Input File 2 line by line
    while (<INF2>){
    
            # Get rid of whitespace
            chomp;
    
            # Initialize key value in case it is not found
            my $geneSymbol = "NA";
    
            # Split the line on tabs
            my ($geneID, $EGF_Baseline, $EGF_Stimulus) = split("\t", $
+_);
    
            # Check if the codon is present in the hash
            if (defined $geneSymbolConversion{$geneID}){
    
                    # Get the value associated with the codon from the
+ hash
                    $geneSymbol = $geneSymbolConversion{$geneID};
            }
    
            # Join data and print to output file
            print OUTF1 join( "\t", $geneID, $geneSymbol, $EGF_Baselin
+e, $EGF_Stimulus), "\n";
    }
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P.S. I will also be reading in the third input file /scratch/Drosophila/gene_association.goa_fly to load columns 3 and 5 from the gene association file into a hash- with column 3 (gene symbol) being the key and column 5 (GO term) the value- then use the hash to convert FlyRNAi_data_baseline_vs_EGFSymbol.txt to FlyRNAi_data_baseline_vs_EGF_GO.txt with the gene symbol replaced by the GO term. If you'd like to provide some tips or mention some potential pitfalls based on my apparent coding habits then please go nuts! Was going to make sure I had this portion of the program running correctly before working in that third element. Mucho gracias!