From: Gary Wright <gwtmp01@...>
Date: 2009-07-19T02:57:10+09:00
Subject: Re: Hash of Hash of Arrays Question


On Jul 18, 2009, at 12:43 PM, Älphä Blüë wrote:
> Does find exactly what I need for any future needs when required.  So,
> at least I learned something.  Now if I could just figure out how to
> sort a hash..

Prior to Ruby 1.9, hashes are unsorted.  In Ruby 1.9, hashes are
maintained in insertion order.  That is to say, if you iterate
over the hash you'll get the key/value pairs in the order in
which they were inserted into the hash.

If you want to iterate over a hash according to some other
order you'll need to do something like:

hash = {2=>1, 1=>0, 3=>4}

hash.sort_by {|k,v| k }.each { |k,v|
   puts "key: #{k}, value: #{v}"
}


key: 1, value: 0
key: 2, value: 1
key: 3, value: 4

Note that sort_by doesn't return a hash but instead returns
an array of key/value pairs:

 >> hash.sort_by { |k,v| v }
=> [[1, 0], [2, 1], [3, 4]]


Gary Wright