I'm looking for a way to join multiple arrays, but in a way that attempts to preserve the order of the elements. Here's what I mean:

my @array1 = (1, 3, 4, 6);
my @array2 = (1, 2, 4, 6);
my @array3 = (1, 2, 3, 5);

my %seen;
my @union = grep { not $seen{$_}++ } (@array1, @array2);
    
undef %seen;
@union = grep { not $seen{$_}++ } (@union, @array3);

print join(' ', @union);
[download]

The output from this script is:
1 3 4 6 2 5

But, as you can see from my original arrays, 2 should come before 3, and 4 should come after 2. Is there a way to intelligently attempt to preserve the proper order of the elements? There will, of course, be data sets that can't be preserved, eg/

@array1 = (1, 2, 3, 4);
@array2 = (1, 3, 2, 4);
[download]

... but the code should handle this gracefully and just choose one over the other.

Any ideas?

Thanks!
clay.

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