From: Aldric Giacomoni <aldric@...>
Date: 2009-10-26T23:09:11+09:00
Subject: Re: Hash Reverse ?

Salai Koko wrote:
> I am preparing for my orals exam in Ruby (my last chance.. , If I fail
> the test, no more possible to study Computer Science related :-) )
> 
> http://codepad.org/foNb9Pd3
> 
> class Hash
>   def hash_revert
>     hash_new = Hash.new
>     self.each {|key,value|
>       if not hash_new.has_key?(key) then hash_new[value] = key end
>     }
>     return hash_new
>   end
> end
> 
> h = {2=>"a", 1=> "b", 3 =>"a", 4=> "a", 5 => "b", 6=>"c"}
> p h.hash_revert #--> {"a"=>4, "b"=>1, "c"=>6}
> 
> or Should I get this ??
> # => {"a"=>2, "b"=>1, "c"=>6}
> 
> Because HASH is working like "Set" ??
> 
> many thanks in advance,
> salai.

In Ruby 1.9, hashes keep the order of input. Before Ruby 1.9, the order 
is "random" - so it's not guaranteed which will be the first key that 
you will see with 'each'.
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