Convert Ruby Array to Ranges

bsiggelkow (Bill Siggelkow) — Fri, 19 Oct 2007 13:03:58 GMT

# Array#to_ranges
# Converts an array of values (which must respond to #succ) to an array of ranges. For example,
# [3,4,5,1,6,9,8].to_ranges => [1,3..6,8..9]



class Array

  def to_ranges

    array = self.compact.uniq.sort

    ranges = []

    if !array.empty?

      # Initialize the left and right endpoints of the range

      left, right = self.first, nil

      array.each do |obj|

        # If the right endpoint is set and obj is not equal to right's successor 

        # then we need to create a range.

        if right && obj != right.succ

          ranges << Range.new(left,right)

          left = obj

        end

        right = obj

      end

      ranges << Range.new(left,right)

    end

    ranges

  end

end

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Convert Ruby Array to Ranges