Ruby method to return an array of Australian Postcodes

postcodes.rb

# Returns an array of Australian Postcodes
def australian_postcodes
  # Postcodes that look like integers
  nsw = (1000..1999).to_a +
        (2000..2599).to_a +
        (2619..2898).to_a +
        (2921..2999).to_a
  act = (2600..2618).to_a +
        (2900..2920).to_a
  vic = (3000..3999).to_a +
        (8000..8999).to_a
  qld = (4000..4999).to_a +
        (9000..9999).to_a
  tas = (7000..7799).to_a +
        (7800..7999).to_a
  sa = (5000..5799).to_a +
       (5800..5999).to_a
  wa = (6000..6797).to_a +
       (6800..6999).to_a

  # Convert integers to strings (postcodes are *not* integers)
  postcodes = (nsw + act + vic + qld + tas + sa + wa).map { |p| p.to_s }

  # Postcodes from NT (and one range in the ACT don't look like integers)
  nt_and_act_range = (800..899).to_a + (900..999).to_a + (200..299).to_a

  postcodes + (nt_and_act_range.map { |p| "0#{p.to_s}" })
end

p australian_postcodes