range-split-usage.rb

require_relative 'range-split'

(1...1000).split(3) #=> [1...334, 334...667, 667...1000]
(1..1000).split(3)  #=> [1...335, 335...669, 669..1000]

range-split.rb

class Range
  def split(split_qty)
    raise ArgumentError, 'infity not supported' unless (
        [self.begin,self.end] & [Float::INFINITY,-Float::INFINITY]
      ).empty?
    chunk_size = Rational(self.count, split_qty).ceil
    splits = self.each_slice(chunk_size).reduce([]) do |memo,split|
      memo << (split.first...split.last.next)
    end

    last_split = splits.pop
    
    splits << Range.new(last_split.begin, self.end, self.exclude_end?)
  end
end