in reply to Bag uniform distribution algorithms
G'day Dave,
By alternatively splicing elements from either end of the distribution, I get your original 'qw( A C B A D C A B C A )'.
$ perl Mstrict Mwarnings E '
my %bag = ( A => 4, B => 2, C => 3, D => 1 );
my @distribution;
for my $key (sort { $bag{$b} <=> $bag{$a} } keys %bag) {
my $base_offset = int(@distribution / ($bag{$key} + 1));
my $offset = $base_offset;
for (1 .. $bag{$key}) {
next unless $_ % 2;
splice @distribution, $offset, 0, $key;
if ($_ < $bag{$key}) {
splice @distribution, $offset, 0, $key;
}
$offset += $base_offset + 1;
}
}
say "@distribution";
'
A C B A D C A B C A
If I round up the $base_offset value, the middle two elements are reversed but everything else remains the same. I don't see this as being more or less uniform but maybe it's more correct.
$ perl Mstrict Mwarnings E '
my %bag = ( A => 4, B => 2, C => 3, D => 1 );
my @distribution;
for my $key (sort { $bag{$b} <=> $bag{$a} } keys %bag) {
my $base_offset = int(@distribution / ($bag{$key} + 1) + 0.5);
+
my $offset = $base_offset;
for (1 .. $bag{$key}) {
next unless $_ % 2;
splice @distribution, $offset, 0, $key;
if ($_ < $bag{$key}) {
splice @distribution, $offset, 0, $key;
}
$offset += $base_offset + 1;
}
}
say "@distribution";
'
A C B A C D A B C A
I haven't done extensive testing on this solution. Beyond your sample input, I tried:
my %bag = ( A => 4, B => 2, C => 3, D => 1, Z => 1 );
gives: A C B A C D Z A B C A; and
my %bag = ( A => 4, B => 2, C => 3, D => 1, Y => 5, Z => 1 );
gives: Y A C Y B A C Z D Y A B Y C A Y; and
my %bag = ( A => 4, B => 2, C => 3, D => 1, X => 6, Y => 5, Z => 1 );
gives: X Y A X C Y B A X Y Z D C X A B Y C X A Y X; and
my %bag = ( A => 4, B => 2, C => 3, D => 1, W => 4, X => 6, Y => 5, Z
+=> 1 );
gives: X Y A W X C Y B A W X Y Z D C X W A B Y C X W A Y X
The above 4 tests all included rounding; without rounding, the results are:
A C B A Z D C A B C A
Y A C Y B A C D Z Y A B Y C A Y
X Y A C X Y B A C X D Z Y X A B Y X C A Y X
X Y A W C X Y B A W C X D Z Y X W A B Y X C W A Y X
