From: Logan Capaldo <logancapaldo@...>
Date: 2006-06-14T16:19:46+09:00
Subject: Re: impossible to sort a hash by key?


On Jun 14, 2006, at 3:03 AM, Oliver Katzer wrote:

> Hi everyone!
>
> is it impossible to sort a hash by key?
>
> I have a hash like {"plums"=>3, "bananas"=>4, "apples"=>6}
>
> And what i want is {"apples" => 6, "bananas" => 4, "plums" => 3}
>
> Hash#sort returns an array. So i've tried this:
>
> class Hash
>   def sort_by_key
>     array = self.sort
>     # the array is sorted!
>     array.inject({}) do |hash, value|
>       hash[value.first] = value.last
>       hash
>     end
>   end
> end
>
> But the result is {"plums"=>3, "bananas"=>4, "apples"=>6}!
>
> So - is it impossible to sort a hash by key?
>
> Oliver.
>
> --  
> Posted via http://www.ruby-forum.com/.
>

A hash's order is not guaranteed. If you want to display the hash in  
sorted order you can do something like the following

% cat sorted_hash.rb
class Hash
   def each_ordered_by_key
      keys.sort.each do |key|
        yield(key, self[key])
      end
   end
end

str = "{"

hash = {"plums"=>3, "bananas"=>4, "apples"=>6}

hash.each_ordered_by_key do |key, value|
   str << "#{key.inspect}=>#{value.inspect}, "
end

str[-2, 2] = "}"

puts str

% ruby sorted_hash.rb
{"apples"=>6, "bananas"=>4, "plums"=>3}