Re: Split a string into a list of lists

If you really want to do it in one, then the following is a way:

  my @array = (undef, map([undef, map($_-64, unpack('C3', $_))],
                                             unpack('(A3)*', $string))
+) ;
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The thing to watch out for with nested maps is the reuse of $_, but in this case it's fine.

Just for the hell of it, I threw a little benchmarking at it:

                Rate       W1SDM GrandFather        GMCH
  W1SDM       7.59/s          --        -30%        -48%
  GrandFather 10.9/s         43%          --        -25%
  GMCH        14.6/s         93%         34%          --

which tells you that this can go almost twice as fast if you throw certain amount of magic at it. The question is: does this affect the price of cocoa ? And the other question is: if so, was the effect worth the effort ?

Update: ah... same trick as AnomalousMonk above.

use strict ;
use warnings ;

my $string = "BEHACJBDLCENADFEGOFHQAGIHJRBIKJLSCKMLNTDMOFNPOQTGPRIQSKR
+TMPS";

my @results = () ;

collect('W1SDM',       W1SDM($string)) ;
collect('GrandFather', GrandFather($string)) ;
collect('GMCH',        GMCH($string)) ;

printf("%12s %12s %12s\n", @$_) foreach @results ;

use Benchmark qw(cmpthese) ;

cmpthese(100, { W1SDM        => sub { W1SDM($string)       for (1..100
+0) },
                GrandFather  => sub { GrandFather($string) for (1..100
+0) },
                GMCH         => sub { GMCH($string)        for (1..100
+0) },
              }
        ) ;

sub collect {
  my ($t, $r) = @_ ;

  push @{$results[0]}, $t ;

  push @{$results[$_]}, sprintf "%02d %02d %02d", @{$r->[$_]}[1..3] fo
+r (1..$#$r);
} ;

sub W1SDM {
  my ($string) = @_ ;

  my @array = split //, $string;
  my @result = () ;

  for my $i (1..20) {
    for my $j (1..3) {
      $result[$i][$j] = ord(shift(@array)) - 64;
    }
  }

  return \@result ;
} ;

sub GrandFather {
  my ($string) = @_ ;

  my @array = (undef);

  push @array, [0, map {ord ($_) - 64} split '', substr $string, 0, 3,
+ '' ]
    while length $string;

  return \@array ;
} ;

sub GMCH {
  my ($string) = @_ ;

  my @array = (undef, map([undef, map($_-64, unpack('C3', $_))],
                                                   unpack('(A3)*', $st
+ring))) ;

  return \@array ;
} ;
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