G'day fidda,

This does what you want: 

#!/usr/bin/env perl

use strict;
use warnings;

use Data::Dump;

my @A = qw{H1 H2 H3 H4};
my @B = 1 .. 10;

my %result;
my $reverse = 0;

while (@B) {
    build_hash(\%result, \@A, \@B, $reverse);
    $reverse ^= 1;
}

dd \%result;

sub build_hash {
    my ($result, $A, $B, $reverse) = @_;

    my @keys = @$B >= @$A ? @$A : @$A[0 .. $#$B];
    my @values;

    if ($reverse) {
        unshift @values, shift @$B for (0 .. $#keys);
    }
    else {
        push @values, shift @$B for (0 .. $#keys);
    }

    push @{$result->{$keys[$_]}}, $values[$_] for 0 .. $#keys;
}

[download]

Output:

{ H1 => [1, 8, 9], H2 => [2, 7, 10], H3 => [3, 6], H4 => [4, 5] }

[download]

Note that this code destroys @B. If you need to keep it, make a copy and use that in the while condition and when calling &build_hash: 

my @B_copy = @B;
...
while (@B_copy) {
    build_hash(\%result, \@A, \@B_copy, $reverse);
...

[download]

Furthermore, the subroutine &build_hash has no reliance on the initial values of either @A or @B. For example, these initial values: 

my @A = qw{H1 H2 H3 H4 H5};
my @B = 1 .. 23;

[download]

produce this output: 

{
  H1 => [1, 10, 11, 20, 21],
  H2 => [2, 9, 12, 19, 22],
  H3 => [3, 8, 13, 18, 23],
  H4 => [4, 7, 14, 17],
  H5 => [5, 6, 15, 16],
}

[download]

— Ken

In reply to Re: How to get this not the usual round robin looping by kcott
in thread How to get this not the usual round robin looping by fidda

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.