Re: What is the best way to get just the duplicates from an array?

Use a hash to count each occurrance and then grep to get those that appear more than once.

my @a = qw/ 1 2 3 4 5 6 7 8 9 5 7 9 /;
my %h;
$h{$_}++ for @a;
my @dups = grep { $h{$_} > 1 } keys %h;
print "@dups\n";
[download]

Is one way.

Comment on Re: What is the best way to get just the duplicates from an array? Download Code

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Re^2: What is the best way to get just the duplicates from an array? by ikegami (Patriarch) on Jul 27, 2007 at 15:03 UTC
Combining your loops into one: `my @a = qw/ 1 2 3 4 5 6 7 8 9 5 7 9 5 /; my %seen; my @dups = grep ++$seen{$_}==2, @a; print "@dups\n";` [download]	[reply] [d/l]
Re^3: What is the best way to get just the duplicates from an array? by FunkyMonk (Bishop) on Jul 27, 2007 at 15:26 UTC
That's damned sneaky. I like it++	[reply]