Re: How to get this not the usual round robin looping


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Re: How to get this not the usual round robin looping

by AnomalousMonk (Archbishop)

on Oct 16, 2015 at 12:44 UTC ( [id://1145110]=note: print w/replies, xml )

Need Help??

in reply to How to get this not the usual round robin looping

Here's a variation on hdb's (nice++) approach that uses List::MoreUtils::part():

c:\@Work\Perl\monks\fidda>perl -wMstrict -le
"use List::MoreUtils qw(part);
 ;;
 use constant KEYS  => qw(H1 H2 H3 H4);
 use constant ITEMS => 'A' .. 'O';
 ;;
 my @steps = map { @$_, reverse @$_ } [ 0 .. KEYS-1 ];
 ;;
 my $i = 0;
 my @parts = part { $steps[ $i++ % @steps ] } ITEMS;
 ;;
 my %h;
 @h{ KEYS() } = @parts;
 for my $k (KEYS) {
   printf qq{$k };
   printf qq{'$_' } for @{ $h{$k} };
   print '';
   }
"
H1 'A' 'H' 'I'
H2 'B' 'G' 'J' 'O'
H3 'C' 'F' 'K' 'N'
H4 'D' 'E' 'L' 'M'
[download]

If you don't like part(), you can use
my @parts;
push @{ $parts[ $steps[ $i++ % @steps ] ] }, $_ for ITEMS;

I kinda don't like the stray $i variable wandering through the code, but if you wrap this all up in a distributor function, this is no longer an issue.

Give a man a fish: <%-{-{-{-<