From: Nasir Khan <rubylearner@...>
Date: 2007-03-01T05:31:30+09:00
Subject: Sorting a Hash

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I want to have a hash with its elements sorted with a custom sort order.
Consider the example

#---------------------
test_hash = {"A" => "first", "B" => "second"}
puts test_hash.keys.join(", ")
order_arr = ["B", "A"]

test_hash.sort do |x,y|
   (order_arr.index(x[0])?order_arr.index(x[0]):order_arr.length) <=>
(order_arr.index(y[0])?order_arr.index(y[0]):order_arr.length)
end
puts test_hash.keys.join(", ")
#----------------------

Output:
  A, B
  A, B
  => true

I want to order such that the keys (or values) when returned in an array are
ordered.
Obviously the above snipper does *not* work because Hash#sort does not sort
the Hash but returns an array of arrays with elements sorted according to
sort block.

I can maintain a parallel array of sorted keys but it is kind of kludgy.
Can I sort the hash "in place" such that the Hash#keys and Hash#values
return sorted results, without me having to maintain this array of arrays
separately?

TIA

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