Question

I am fairly new to Perl so hopefully this has a quick solution.

I have been trying to combine two files based on a key. The problem is there are multiple values instead of the one it is returning. Is there a way to loop through the hash to get the 1-10 more values it could be getting?

Example:

File Input 1:

12345|AA|BB|CC
23456|DD|EE|FF

File Input2:

12345|A|B|C
12345|D|E|F
12345|G|H|I
23456|J|K|L
23456|M|N|O
32342|P|Q|R

The reason I put those last one in is because the second file has a lot of values I don’t want but file 1 I want all values. The result I want is something like this:

WANTED OUTPUT:

12345|AA|BB|CC|A|B|C
12345|AA|BB|CC|D|E|F
12345|AA|BB|CC|G|H|I
23456|DD|EE|FF|J|K|L
23456|DD|EE|FF|M|N|O

Attached is the code I am currently using. It gives an output like so:

OUTPUT I AM GETTING:

12345|AA|BB|CC|A|B|C
23456|DD|EE|FF|J|K|L

My code so far:

#use strict; 
#use warnings; 

open file1, "<FILE1.txt"; 
open file2, "<FILE2.txt"; 

while(<file2>){

    my($line) = $_; 
    chomp $line; 
    my($key, $value1, $value2, $value3) = $line =~ /(.+)\|(.+)\|(.+)\|(.+)/; 
    $value4 = "$value1|$value2|$value3"; 
    $file2Hash{$key} = $value4; 
} 

while(<file1>){ 

    my ($line) = $_; 
    chomp $line; 
    my($key, $value1, $value2, $value3) = $line =~/(.+)\|(.+)\|(.+)\|(.+)/; 

    if (exists $file2Hash{$key}) {

        print $line."|".$file2Hash{$key}."\n";
    } 
    else {
        print $line."\n";
    } 
} 

Thank you for any help you may provide,

Answer 1

Your overall idea is sound. However in file2, if you encounter a key you have already defined, you overwrite it with a new value. To work around that, we store an array(-ref) inside our hash.

So in your first loop, we do:

push @{$file2Hash{$key}}, $value4; 

The @{...} is just array dereferencing syntax.

In your second loop, we do:

if (exists $file2Hash{$key}){
  foreach my $second_value (@{$file2Hash{$key}}) {
    print "$line|$second_value\n";
  }
} else {
  print $line."\n";
}

Beyond that, you might want to declare %file2Hash with my so you can reactivate strict.