ruby on rails - All variants of an array -

ruby on rails - All variants of an array -

i have array structured one:

array = ["one","two","three","four"];

how can possible variants of array, in possible lengths 1-4:

ar = [["one"]["two"]["three"]["four"]["one","two"] ["one","three"] ["one","three","four"]]

i think in end there should 4*4*4*4 elements in array.

how can possible variants of array[...]

use array#combination:

array.combination(3).to_a

result:

[["one", "two", "three"], ["one", "two", "four"], ["one", "three", "four"], ["two", "three", "four"]]

[...]in possible lengths 1-4

use range, iterate on enumerable#flat_map:

(1..array.length).flat_map {|len| array.combination(len).to_a }

result:

[["one"], ["two"], ["three"], ["four"], ["one", "two"], ["one", "three"], ["one", "four"], ["two", "three"], ["two", "four"], ["three", "four"], ["one", "two", "three"], ["one", "two", "four"], ["one", "three", "four"], ["two", "three", "four"], ["one", "two", "three", "four"]]

ruby-on-rails ruby arrays ruby-on-rails-3 combinatorics