Here is one way of doing it using grep.

    #!/usr/bin/perl -w

    use strict;

    my @array = ([1], [2], [3], [4], [5]);
    my %skip  = (3 => 1);

    my @keep  = grep {not exists $skip{$_->[0]}} @array;
    my @skip  = grep {    exists $skip{$_->[0]}} @array;

    my @new   = (@keep, @skip);
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If the array of data is very large it may be inefficient to use two calls to grep. In which case a while loop solution as shown by grinder would be better.

--
John.