Dynamically create 2d array ruby

Question

Is it possible to create the following 2d array dynamically:

[[1, 1], [1, 2], [2, 1], [2, 2], [3, 1], [3, 2], [4, 1], [4, 2]]

Eg.

(1..4).to_a
#=> [1, 2, 3, 4]
(1..2).to_a
#=> [1, 2]

Combine this somehow?

Answer 1

Array#product is the method you're looking for:

(1..4).to_a.product (1..2).to_a

Answer 2

This sounds a bit like a homework question. It would be nice to get context around what you're trying to do. You'll want to spend some time researching the different loops/iterators that ruby provides you. Here is a method that will return the array you're looking for by using one of ruby's iterator methods upto.

def generate_array
  arr = []

  1.upto(4) do |y|
    1.upto(2) do |x|
      arr << [y, x]
    end
  end

  arr
end