From: Massimiliano Mirra <list@...>
Date: 2002-01-07T00:15:51+09:00
Subject: [ruby-talk:30349] Re: OT: Re: Sorting a Hash by value of integer stored in the Hash

On Sun, Jan 06, 2002 at 09:15:56PM +0900, Michal Rokos wrote:
> >    Hash[ *ary.flatten ]
> 	OK, this works, but let's imagine another ex.:
> 	a = [[1,[2,3]],[4,[5,6]]]
> 	I want {1=>[2,3], 4=>[5,6]}, not {1=>2, 3=>4, 5=>6}... :-)

Well, so you'll have to convert it to something acceptable from Hash
constructor, won't you? ;-)

old = [[1,[2,3]],[4,[5,6]]]

new = []

old.each {|item| new.concat item}

Hash[*new]

Something more general:

class Array
  # Flatten n levels (one by default)
  #
  def flatten2(level = 1)
    flattened = []
    each do |item|
      if item.kind_of?(Array)
	flattened.concat item
      else
	flattened.push item
      end
    end
    flattened = flattened.flatten2(level-1) if level > 1
    return flattened
  end
end


if $0 == __FILE__
  require 'Lapidary/TestCase'
  
  class TestArray < Lapidary::TestCase
    def testFlattenLevel1
      a = [[1,[2,3]], [4,[5,6]]]

      assert_equal [1, [2, 3], 4,[5, 6]], a.flatten2
    end

    def testFlattenLevel2
      a = [[1, [2, 3]], [4, [5, 6]]]

      assert_equal [1, 2, 3, 4, 5, 6], a.flatten2(2)
    end

    def testFlattenLevelN
      a = [[1, [2, [3, 4]]], [5, [6, [7, 8]]]]

      assert_equal [1, [2, [3, 4]], 5, [6, [7, 8]]], a.flatten2

      assert_equal [1, 2, [3, 4], 5, 6, [7, 8]], a.flatten2(2)
      
      assert_equal [1, 2, 3, 4, 5, 6, 7, 8], a.flatten2(3)
    end
  end
  
  require 'Lapidary/UI/Console/TestRunner'
  Lapidary::UI::Console::TestRunner.run(TestArray)
end


I hope nobody minds me posting tests along with snippets.  They take
more bandwidth but I find them easier to understand than explanations,
however well crafted they are.



Massimiliano