From: Handy Gandy <handigandy-es@...>
Date: 2010-09-15T02:31:38+09:00
Subject: Re: Iterate over a cartesian product.

On Tue, 14 Sep 20 10 17:13:11 +0200, J旦rg W Mittag wrote:

> Handy Gandy wrote:
>> I have an array of N arrays A_i: [A_1,A_2,...,A_N].
>> 
>> I want to iterate over the cartesian product A_1xA_2...xA_N.
>> 
>> Is there a simple way of doing this without specifying N?
> 
>     ary = [[1, 2], [3, 4, 5], [6, 7, 8, 9]]
>     ary.first.product(*ary.drop(1))
>     # => [
>     # =>   [1, 3, 6], [1, 3, 7], [1, 3, 8], [1, 3, 9], # =>   [1, 4, 6],
>     [1, 4, 7], [1, 4, 8], [1, 4, 9], # =>   [1, 5, 6], [1, 5, 7], [1, 5,
>     8], [1, 5, 9], # =>   [2, 3, 6], [2, 3, 7], [2, 3, 8], [2, 3, 9], #
>     =>   [2, 4, 6], [2, 4, 7], [2, 4, 8], [2, 4, 9], # =>   [2, 5, 6],
>     [2, 5, 7], [2, 5, 8], [2, 5, 9] # => ]
> 
> jwm

That looks so cool I wish I knew what it does.