From: Brian Candler <b.candler@...>
Date: 2010-03-09T22:15:58+09:00
Subject: Re: Flatten out Hash

Glenn Ritz wrote:
> Hi,
> 
> I would like to take a nested hash that looks like this:
> 
> {"a"=>{"b"=>{"c"=>1}, "b2"=>{"c2"=>2}}}
> 
> and turn it into an array of 2 element arrays like this:
> 
> [["a: b2: c2: ", 2], ["a: b: c: ", 1]]
> 
> Is there a simple way to do this?  I wrote a method that iterates
> through the nested hashes recursively, but it's a bit cumbersome.

I think that's the right way, if the nesting depth is variable. One 
example:

class Hash
  def flat_each(prefix="", &blk)
    each do |k,v|
      if v.is_a?(Hash)
        v.flat_each(prefix+k+": ", &blk)
      else
        yield prefix+k, v
      end
    end
  end
end

require 'enumerator'
h = {"a"=>{"b"=>{"c"=>1}, "b2"=>{"c2"=>2}}}
p h.to_enum(:flat_each).collect { |k,v| [k,v] }
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