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rubyarraysalgorithmcombinationscombinatorics
Max Bublikoff
Max Bublikoff

Reputation: 1234

All combinations of array

I have array

a = ["w1", "w2", "w3"]

How can I generate a new array with every combination of values? I need the output to look like this:

["w1", "w2", "w3", "w1 w1", "w1 w2", "w1 w3", "w2 w1", "w2 w2", "w2 w3", "w3 w1", "w3 w2", "w3 w3", "w1 w1 w1", "w1 w1 w2", "w1 w1 w3", "w1 w2 w1", "w1 w2 w2", "w1 w2 w3", "w2 w1 w1", "w2 w1 w2", "w2 w1 w2", "w2 w1 w3", "w2 w2 w1", "w2 w2 w2", "w2 w2 w3", "w2 w3 w1", "w2 w3 w2", "w2 w3 w3", "w3 w1 w1", "w3 w1 w2", "w3 w1 w3", "w3 w2 w1", "w3 w2 w2", "w3 w2 w3", "w3 w3 w1", "w3 w3 w2", "w3 w3 w2"]

Try code from Generate array of all combinations of an existing array

Result incorrect

"w1", "w2", "w3", "w1 w2", "w1 w3", "w2 w3", "w1 w2 w3"]

Upvotes: 2

Views: 866

Answers (1)

hirolau
hirolau

Reputation: 13901

Here is one way to do it, however this result has "w3 w3 w3" and you desired result does not, but I do not see the logic to include "w3 w3" and "w1 w1 w1" but not "w3 w3 w3", so I assume you just missed to add that.

What you are looking for is not the combinations, but the permutations (with repetation):

a = ["w1", "w2", "w3"]

result = (1..a.size).flat_map do |size|
  a.repeated_permutation(size).map { |perm| perm.join(' ') }
end

Upvotes: 5

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