Find all permutations of Ruby array of arrays

Question

Let's say I have the following input array of arrays:

[[1],[2,3],[4,5],[6]]

I'd like to produce all permutations like this:

[[1,2,4,6],[1,2,5,6],[1,3,4,6],[1,3,5,6]]

What's a nice Ruby way of doing this? Or really any way of doing this? I feel like there's an elegant solution that I can't see.

eugen · Accepted Answer · 2014-01-21 22:13:27Z

7

What you need is the cartesian product. Something like:

[1].product([2,3],[4,5],[6]) # => [[1, 2, 4, 6], [1, 2, 5, 6], [1, 3, 4, 6], [1, 3, 5, 6]]

answered Jan 21, 2014 at 22:13

eugen

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2 Comments

aardvarkk Over a year ago

So how does one generalize this? Let's say my initial array is arr... is this arr[0].product(arr[1..-1]) or something? (It's not, I've tried it :))

eugen Over a year ago

Almost - you need to splat the arguments to product, as in arr[0].product(*arr[1..-1])

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