Comparing values within a Hash of Arrays

TJRandall has asked for the wisdom of the Perl Monks concerning the following question:

I am comparing lists of invalid database objects, and trying to determine when values in the second list don't match the values in the first list. (I have to warn the user, via a Jenkins build, when the list has grown and/or new values have appeared)

The exists block fails at runtime, but I cannot figure out a clean, easy way to traverse the 'postbuilds' array to check if the value exists. Any help/pointers would be GREATLY appreciated!

#!/usr/bin/perl  

use strict;
use warnings;
use Data::Dumper;

my @array1 = ( "proc1", "proc2", "proc3", "proc4" );
my @array2 =
  ( "proc1", "proc2", "proc3", "proc4", "proc5" );

my %HoA = (
            prebuilds  => [@array1],
            postbuilds => [@array2],
);

print Dumper \%HoA;

while ( my ( $key, $reference ) = each %HoA ) {
    foreach my $temp ( @{$reference} ) {
        print "key: $key, temp: $temp\n";

        #  look to see if a value in the postbuild list
        # exists in the prebuild list
        if ( exists( $HoA{'postbuild'}->$temp ) ) {
            print "yes\n";
        }
        else { print "no\n"; }
    }
}
[download]

Thank you!

Comment on Comparing values within a Hash of Arrays Download Code

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Re: Comparing values within a Hash of Arrays by stevieb (Canon) on Apr 24, 2012 at 14:22 UTC
You can't use exists in this case, as you are not looking to see if a hash key exists, you need to check within the array to see if an element exists. Here's an example of what I think you want to achieve: `#!/usr/bin/perl use strict; use warnings; use Data::Dumper; use List::Util qw( first ); my @array1 = ( "proc1", "proc2", "proc3", "proc4" ); my @array2 = ( "proc1", "proc2", "proc3", "proc4", "proc5" ); my %HoA = ( prebuilds => [@array1], postbuilds => [@array2], ); for my $postbuild ( @{ $HoA{ postbuilds } } ){ print "$postbuild: "; if ( first { $_ =~ $postbuild } @{ $HoA{ prebuilds } } ){ print "yes\n"; } else { print "no\n"; } }` [download]	[reply] [d/l]
Re^2: Comparing values within a Hash of Arrays by TJRandall (Sexton) on Apr 24, 2012 at 14:30 UTC
Ha! Just saw your edit - did the same, because your direction/suggestion was spot on! Thank you to everyone for replying!	[reply]
Re^3: Comparing values within a Hash of Arrays by stevieb (Canon) on Apr 24, 2012 at 14:34 UTC
I just edit it back :) Let me know which way you needed it originally and I'll fix it permanently	[reply]
Re^4: Comparing values within a Hash of Arrays by TJRandall (Sexton) on Apr 24, 2012 at 15:36 UTC
Re: Comparing values within a Hash of Arrays by Anonymous Monk on Apr 24, 2012 at 14:17 UTC
Like this `sub Fompare { my( $pree, $post ) = @_; for my $item ( @{ $pree } ){ print "$item\n"; print "yes\n" if InIt( $item, $post ); } } sub InIt { my( $item, $post ) = @_; for my $postItem ( @$post ){ return !!1 if $item eq $postItem; return !!1 if $item == $postItem; } }` [download] But see references quick reference and grep	[reply] [d/l]
Re: Comparing values within a Hash of Arrays by tommyxd (Acolyte) on Apr 24, 2012 at 14:18 UTC
If the value you're looking for does not exist in `postbuilds` its value should be `undef`, which is evaluated as `false` in a conditional expression. Therefor I think you could just do: `if ($HoA{'postbuild'}->$temp) { print "yes\n"; }` [download] Hope this helps!	[reply] [d/l] [select]