Remove duplicates from Hash of Arrays

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

Hello, this is probably a simple question but I'm a bit lost. I have a Hash of Arrays structure and I want to get every element of the arrays in one single array. This works but it doesn't remove the duplicates. Is there a simple way to remove duplicates at the same time?

my $HoA = {
   'music' => [9, 53, 3, 15],
   'conferences' => [7, 56, 15],
};
my @ids;
for my $ary ( values %$HoA ) {
   push(@ids,@$ary);
}
print "@ids";

# 9 53 3 15 7 56 15
[download]

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Re: Remove duplicates from Hash of Arrays by Kenosis (Priest) on Dec 09, 2013 at 20:42 UTC
Perhaps the following will be helpful: `use strict; use warnings; my %h; my $HoA = { 'music' => [ 9, 53, 3, 15 ], 'conferences' => [ 7, 56, 15, 53 ], }; @h{@$_} = undef for values %$HoA; my @ids = keys %h; print "@ids"; # 53 56 3 7 9 15` [download] What is this `@h{@$_} = undef` notation? See Hash from two arrays.	[reply] [d/l] [select]
Re^2: Remove duplicates from Hash of Arrays by Anonymous Monk on Dec 09, 2013 at 22:00 UTC
Thanks, I will use this. After some reading up it seems setting each key to undefined can save memory when dealing with large arrays, as I sometimes will be.	[reply]
Re: Remove duplicates from Hash of Arrays by hdb (Monsignor) on Dec 09, 2013 at 20:45 UTC
`my @ids = keys %{{ map { $_ => 1 } map { @$_ } values %$HoA }};` [download]	[reply] [d/l]
Re: Remove duplicates from Hash of Arrays by LanX (Saint) on Dec 09, 2013 at 20:41 UTC
yes, instead of pushing to an array set keys in a hash. `keys %hash` will return you a set w/o duplicates. Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l]
Re: Remove duplicates from Hash of Arrays by wind (Priest) on Dec 09, 2013 at 22:16 UTC
From perldoc: How can I remove duplicate elements from a list or array? - Miller	[reply]
Re: Remove duplicates from Hash of Arrays by Anonymous Monk on Dec 09, 2013 at 21:53 UTC
Thank you for your helpful and informative replies	[reply]