Date: 5 Oct 2001 01:07:38 GMT
From: damian@qimr.edu.au (Damian James)
Subject: Re: Multiplexing strings
Message-Id: <slrn9rq1ph.nup.damian@puma.qimr.edu.au>

On 4 Oct 2001 15:46:21 -0700, Dimitri said:
>I have N=3 strings of equal length, and I want to multiplex them by taking
>M=2 characters from each string (the length of each string is divisible by
>M). Example :
>
>Input:
>
>$str1 = "aabbccddeeff";
>$str2 = "AABBCCDDEEFF";
>$str3 = "001122334455";
>
>Output :
>
>$out = "aaAA00bbBB11ccCC22ddDD33eeEE44ffFF55";
>
>Besides the obvious for loop :
>
>$out = ""; $len = length($str1);
>
>for ($i = 0; $i < $len; $i += 2) {
> $out .= substr($str1, $i, 2) . substr($str2, $i, 2) . substr($str3, $i, 2);
>}
>
>Is there a more elegant (faster) way?

Don't know about faster, certainly less memory efficient, but in any case
a workable Other Way To Do It:

#!/usr/bin/perl 
use warnings;
use strict;

my @str = qw ( aabbccddeeff AABBCCDDEEFF 001122334455 );
my @seq = map { [ /(..)/g ] } @str;
my $out = join '',
		  map {  $seq[0]->[$_], $seq[1]->[$_], $seq[2]->[$_] }
          0..5;
print "$out\n";

I'm sure someone can think of a neater way to handle that map().

Cheers,
Damian
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