Perl: Rearrange array based on element value -

what efficient way rearrange array elements ordered & place corresponding index value (minus one)? $dat variable being max number of elements (which never exceeded in array may or may not present).

$dat = 14;   @array = (1, 12, 14, 7, 8, 4) 

in other words:

my @new_array = (1, undef, undef, 4, undef, undef, 7, 8, undef, undef, undef, 12, undef, 14); 

***edit**** fuller code snippet:

foreach $auth (keys %activity) { @value = @{ $activity{$auth} }; @value = uniq @value; @value = sort @value; s/^0// @value;  $count = scalar(grep $_, @value); $dat = max( @value ); @{$activity{$auth}} = @value; } 

you can create new array values defined after finding maximum value in first, in new array undefine value not in first:

use strict; use warnings; use data::dumper;   @array =  ('1', '4', '3'); $max = (sort { $b <=> $a } @array)[0]; #should 4  print dumper(\@array);  @new_arr; foreach $index (0 .. ($max - 1)) {    $new_arr[$index] = ($index + 1);            #array should populated, @new_arr = ('1', '2', '3', '4');    $new_arr[$index] = 'undef' unless (grep {$_ eq $new_arr[$index]} @array);         #values not in original array should set undef  } #  @new_arr should (''1', 'undef', '3', '4')  print dumper(\@new_arr);  

output:

$var1 = [           '1',           '4',           '3'         ];  $var1 = [           1,           'undef',           3,           4         ];