From: Gary Boone <dr@...>
Date: 2006-12-08T12:28:39+09:00
Subject: Re: [Puzzle] How to do parameter variation?


Cool. While I study the others, here's my solution. Looks like it's 
similar to Greg's.

--Gary


#   expand_hash_lists
#
#   note that accumulating lists must be passed in as the first argument
#
def expand_hash_lists(a1, a2)
  a1.inject([]){|acc,f| a2.inject(acc){|a,b| a << [b]+ 
(f.is_a?(Hash)?[f]:f)}}
end

if __FILE__ == $0

  # tests of expand_hash_lists
  ah=[{'a'=>1}, {'a'=>2}, {'a'=>3}]
  bh=[{'b'=>21}, {'b'=>22}, {'b'=>23}]
  ch=[{'c'=>31}, {'c'=>32}, {'c'=>33}]
  dh=[{'d'=>41}, {'d'=>42}, {'d'=>43}]

  abh = expand_hash_lists(ah, bh)
  abch = expand_hash_lists(abh, ch)
  p expand_hash_lists(abch, dh).inspect

  # Additional tests
  p "----"
  p [[{'a'=>1}], [{'b'=>2}]].inject{|acc, vl| expand_hash_lists(acc, 
vl)}.inspect
  p "----"
  p [[{'a'=>1}, {'a'=>3}], [{'b'=>2}]].inject{|acc, vl| 
expand_hash_lists(acc, vl)}.inspect
  p "----"
  p [[{'a'=>1}, {'a'=>3}], [{'b'=>2}, {'b'=>4}]].inject{|acc, vl| 
expand_hash_lists(acc, vl)}.inspect
end

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