Sort strings and numbers in Ruby

Question

I want to sort an array by strings first and then numbers. How do I do this?

Answer 1

Normally, alphabetization is done with numbers first. If you want to alphabetize something where letters are alphabetized before numbers, you will need to alter the compare function used.

# I realize this function could be done with less if-then-else logic,
# but I thought this would be clearer for teaching purposes.
def String.mysort(other)
  length = (self.length < other.length) ? self.length : other.length
  0.upto(length-1) do |i|
    # normally we would just return the result of self[i] <=> other[i]. But
    # you need a custom sorting function.
    if self[i] == other[i]
      continue # characters the same, skip to next character.
    else
      if self[i] ~= /[0-9]/
        if other[i] ~= /[0-9]/
          return self[i] <=> other[i]  # both numeric, sort normally.
        else
          return 1  # self is numeric, other is not, so self is sorted after.
        end
      elsif other[i] ~= /[0-9]/
        return  -1  # self is not numeric, other is, so self is sorted before.
      else
        return self[i] <=> other[i]    # both non-numeric, sort normally.
      end
    end
  end

  # if we got this far, the segments were identical. However, they may
  # not be the same length. Short sorted before long.
  return self.length <=> other.length
end

['0','b','1','a'].sort{|x,y| x.mysort(y) } # => ['a', 'b', '0', '1']