Excellent!

I was just playing around with your first lot of code when you posted your second update! :-) This works really well, and I can definitely take this idea and run with it.

I noticed that it seemed to have a tendency to use the earlier layouts - most books seemed to often use layouts 1-6, but rarely the later layouts.

I assumed this was because the layouts were always being presented to the regex engine in the same order. Indeed, if I tweak your second example to randomise the order, it seems to use a more general spread of layouts, with the (interesting?) side effect of generating a different valid book each time.

Then I noticed that in your second example at least, the photos aren't necessarily all used. I assumed I can prepend a '^' and append a '$' to the regexp, and this seems to resolve the issue.

I'm hence left with:

use warnings;
use strict;

my $desired_page_count = 10;
# Structure holding all the different page layouts. ('l' = Landscape, 
+'p' = Portrait)
my $pages = {
    ll   => '01',
    pp   => '02',
    lp   => '03',
    pl   => '04',
    lpp  => '05',
    pll  => '06',
    plp  => '07',
    lpl  => '08',
    lll  => '09',
    ppp  => '10',
    ppl  => '11',
    llp  => '12',
    ppll => '13',
    llpp => '14',
};

# Construct a hash of regexen: each value is all the patterns except f
+or the
# key. This way, they don't need to be constructed repeatedly during t
+he matching
my @patterns =  keys %$pages;
my %all_except = map {my $k=$_; ($k => join '|', sort {rand(1) <=> ran
+d(1)} grep {$_ ne $k} @patterns)} @patterns;

my $photos = "llppllpplpppllplpplpplpllplpll";
# Make a really long layout 
$photos .= substr 'lp', rand 2 for 1..50;
$desired_page_count = int( length($photos)/ 2.7 );

my $page_regex = join '|', sort {rand(1) <=> rand(1)} @patterns;
my $regex = "^($page_regex)";
$regex .= "((??{\$all_except{\$$_}}))" for 1..($desired_page_count - 1
+);
$regex .= "\$";
print "\$regex is $regex\n";

use re 'eval';
if (my @pages = $photos =~ /$regex/) {
   print "$pages->{$_}\n" for @pages;
}
else {
   print "Could not come up with no-repeat layout in $desired_page_cou
+nt pages\n";
}

[download]

Thanks for all your help, Roy. ++ your posts.

Regards
Neil

In reply to Re^4: Algorithm to fit photos into spaces on pages by SmugX
in thread Algorithm to fit photos into spaces on pages by SmugX

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