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Re: combinations of multiple variables which can assume multiple values

by LanX (Archbishop)
on Mar 16, 2018 at 15:01 UTC ( #1211069=note: print w/replies, xml ) Need Help??


in reply to combinations of multiple variables which can assume multiple values

straight forward,

the solution for n columns constructed from n-1 columns successively.

use strict; use warnings; use Data::Dump qw/pp dd/; my @a = 1 .. 3; my @b = "a".."b"; my @c =([]); # init one empty row for my $l (@a) { my @old = @c; @c =(); for my $r (@b) { for my $row (@old) { push @c, [ @$row , [$l,$r] ]; #push @c, [ (map [@$_], @$row) , [$l,$r] ]; # copy old-pairs +to new arrays } } #pp "old $l: ",@old; } warn "final:\n"; pp $_ for @c; pp \@c;
[[1, "a"], [2, "a"], [3, "a"]] [[1, "b"], [2, "a"], [3, "a"]] [[1, "a"], [2, "b"], [3, "a"]] [[1, "b"], [2, "b"], [3, "a"]] [[1, "a"], [2, "a"], [3, "b"]] [[1, "b"], [2, "a"], [3, "b"]] [[1, "a"], [2, "b"], [3, "b"]] [[1, "b"], [2, "b"], [3, "b"]]

NB: many subarray-refs repeat

do { my $a = [ [[1, "a"], [2, "a"], [3, "a"]], [[1, "b"], [2, "a"], [3, "a"]], ['fix', [2, "b"], [3, "a"]], ['fix', [2, "b"], [3, "a"]], ['fix', 'fix', [3, "b"]], ['fix', 'fix', [3, "b"]], ['fix', 'fix', [3, "b"]], ['fix', 'fix', [3, "b"]], ]; $a->[2][0] = $a->[0][0]; $a->[3][0] = $a->[1][0]; $a->[4][0] = $a->[0][0]; $a->[4][1] = $a->[0][1]; $a->[5][0] = $a->[1][0]; $a->[5][1] = $a->[1][1]; $a->[6][0] = $a->[0][0]; $a->[6][1] = $a->[2][1]; $a->[7][0] = $a->[1][0]; $a->[7][1] = $a->[3][1]; $a; }

if you want to avoid this, swap the comments in the push lines.

update

added version with tuple copy for non-shared refs

update

toggle the loops to have the order you (probably) wanted

for my $row (@old) { for my $r (@b) {

final: [[1, "a"], [2, "a"], [3, "a"]] [[1, "a"], [2, "a"], [3, "b"]] [[1, "a"], [2, "b"], [3, "a"]] [[1, "a"], [2, "b"], [3, "b"]] [[1, "b"], [2, "a"], [3, "a"]] [[1, "b"], [2, "a"], [3, "b"]] [[1, "b"], [2, "b"], [3, "a"]] [[1, "b"], [2, "b"], [3, "b"]]

Cheers Rolf
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