in reply to Finding duplicate keys

If you know the keys are unique within each table, one shortcut might be to notice the second time you saw each key in a scan of both: 
my @dups = do {
  my %count;
  grep ++$count{$_} == 2, @keys_from_one, @keys_from_two;
};

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Re: •Re: Finding duplicate keys
by pg (Canon) on Apr 04, 2003 at 18:44 UTC
    This piece of code really has a performance issue, as internally it uses "brutal force". I bench marked this against Ovid's code, this one took 93 seconds when Ovid's only took 6 seconds, for the same array size. 
    @keys1 = (1..1000000); #array names would be modified to match the plu
+g-in code
for (my $a = 2; $a < 1000000; $a += 2) {
    push @keys2, $a; ##array names would be modified to match the plug
+-in code
}

my $t0 = time();
#plug the code here
print time() - $t0;

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