There is a memory tickling the back of my brain that disagrees with you. As I understand/remember it, perl implements arrays as linked lists. splice'ing nodes should not "shift the whole end of the array". This vague memory says perl's lists were explicitly designed to make this kind of stuff work well.

My opinion of Benchmark is very low - the results I generated seems to support this vauge memory of mine. 

#!/os/dist/bin/perl -w

use Benchmark;

my @array = 0..10000;

my @idxsToRemove = ();
push @idxsToRemove, int( rand( 10000 ) ) for ( 0 .. 100 );

my %toRemoveIdx;
@toRemoveIdx{@idxsToRemove} = (1)x@idxsToRemove;

sub Tye {
    my @subarray = @array;

    @subarray = map { $toRemoveIdx{$_} ? () : $subarray[$_] } 0..$#sub
+array;
}

sub btrott {
    my @subarray = @array;

    splice @subarray, $_, 1 for sort { $b <=> $a } @idxsToRemove;
}
imethese( shift @ARGV || -5, 
           {
               'Tye' => \&Tye,
               'btrott' => \&btrott,
            }
         );

[download]

Generated these results: 

 Benchmark: running Tye, btrott, mikfire, each for at least 5 CPU seco
+nds...
       Tye:  7 wallclock secs ( 5.98 usr +  0.00 sys =  5.98 CPU) @  7
+.19/s (n=43)
    btrott:  6 wallclock secs ( 5.38 usr +  0.00 sys =  5.38 CPU) @ 63
+.01/s (n=339)

[download]

mikfire

In reply to RE: Re: Removing certain elements from an array by mikfire
in thread Removing certain elements from an array by Anonymous Monk

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