perl - all possible combinations of hash - perl

Question

tell me how to get every possible combination of hash
Here is an example
my %data = (
'a' => [qw(a1 a2 a3)],
'b' => [qw(b1 b2 b3)],
'c' => [qw(c1 c2 c3)]);
to get
a1
a2
a3
b1
b2
b3
c1
c2
c3
a1 b1
a1 b2
a1 b3
a1 c1
a1 c2
a1 c3
b1 c1
b1 c2
b1 c3
b2 c1
b2 c2
b2 c3
b3 c1
b3 c2
b3 c3
a1 b1 c1
a1 b1 c2
a1 b1 c3
a1 b2 c1
a1 b2 c2
a1 b2 c3
a1 b3 c1
a1 b3 c2
a1 b3 c3
a2 b1 c1
a2 b1 c2
a2 b1 c3
a2 b2 c1
a2 b2 c2
a2 b2 c3
a2 b3 c1
a2 b3 c2
a2 b3 c3
a3 b1 c1
a3 b1 c2
a3 b1 c3
a3 b2 c1
a3 b2 c2
a3 b2 c3
a3 b3 c1
a3 b3 c2
a3 b3 c3
thanks

Answer 1

Use brian d foy's Set::CrossProduct module. You'll need to massage your hash into array of arrays in an obvious way.
use Set::CrossProduct;
my $iterator = Set::CrossProduct->new( ARRAY_OF_ARRAYS );
my $tuples = $iterator->combinations;

Answer 2

My module List::Gen contains a cartesian function that can produce the results you want. This code seems to do the trick, but your example does not contain all of the permutations that this will produce, which I am assuming is just an omission in the example.
use List::Gen 'cartesian';
my %data = (
'a' => [qw(a1 a2 a3)],
'b' => [qw(b1 b2 b3)],
'c' => [qw(c1 c2 c3)],
);
my $product = cartesian {join ' ' => sort grep defined, #_}
map {[#$_, undef]}
values %data;
say for sort {length $a <=> length $b or $a cmp $b} #$product;
That is a bit dense, so to explain:
values %data returns the arrays in %data
map {[#$_, undef]} then attaches an empty value to the end of each, since you want the partial combinations
cartesian {join ' ' => sort grep defined, #_} then does the meat of the work, computing the Cartesian product of the arrays while subtracting out the undefined elements, and sorting the values as your example shows.
sort {length $a <=> length $b or $a cmp $b} #$product then prints out the product in the order specified.