Question

I need a ruby formula to create an array of integers. The array must be every other 2 numbers as follows.

[2, 3, 6, 7, 10, 11, 14, 15, 18, 19...]

I have read a lot about how I can do every other number or multiples, but I am not sure of the best way to achieve what I need.

Answer 1

Here’s an approach that works on any array.

def every_other_two arr
  arr.select.with_index do |_, idx|
    idx % 4 > 1
  end
end

every_other_two((0...20).to_a) # => [2, 3, 6, 7, 10, 11, 14, 15, 18, 19]

# it works on any array
every_other_two %w{one two three four five six} # => ["three", "four"]