From: Bil Kleb <Bil.Kleb@...>
Date: 2008-01-07T21:00:00+09:00
Subject: compact or uniq that takes a block like sort?

Hi,

I'm looking for an elegant way to do the following:

  Given an sorted array of (X,Y) pairs where Y is strictly
  increasing, i.e., no repeated Ys.

  Compact pairs with repeated Xs, keeping the pair with
  the highest Y value.

E.g.,

  require 'test/unit'

  class TestConsolidation < Test::Unit::TestCase
    def test_should_remove_repeated_Xs_but_save_one_with_highest_Y
      initial = [ [ 1, 12 ], [ 3, 15 ], [ 3, 17 ], [ 3, 22 ], [ 7, 45 ] ]
      desired = [ [ 1, 12 ], [ 3, 22 ], [ 7, 45 ] ]
      assert_equal desired, initial.consolidate
    end
  end

  class Array
    def consolidate
      # Too embarrassed to show current hack.
    end
  end

My least surprise inclination had me researching #uniq and #compact
to see if they took a block like #sort.

Thanks,
--
Bil Kleb
http://fun3d.larc.nasa.gov