From: zdennis <zdennis@...>
Date: 2005-11-05T11:43:13+09:00
Subject: Re: How does one sort hash of hashes by multiple values?

zdennis wrote:
> joe.yakich@gmail.com wrote:
> 
>> Imagine I have this data structure:
>>
>>      @my_hash[8858]['name'] = 'goober'
>>      @my_hash[8858]['sort_date'] = 19991231
>>
>>      @my_hash[2004]['name'] = 'goober'
>>      @my_hash[2004]['sort_date'] = '20010416'
>>
>>      @my_hash[8872]['name'] = 'pyle'
>>      @my_hash[8872]['sort_date'] = '20010416'
>>
>>      @my_hash[89]['name'] = 'hogan'
>>      @my_hash[89]['sort_date'] = '2004 0918'
>>
>>      @my_hash[9]['name'] = 'homer'
>>      @my_hash[9]['sort_date'] = '19980718'
>>
>> How does one sort it first by the name value, then by the sort_date
>> value? (So that the name == 'goober' items appear before the others,
>> and the very first element returned by the sort would be
>> @my_hash[8858]?)
>>
>> I tried searching a bit (the FAQ and google) , but came up empty; sorry
>> if this is a noob question. (Although, I am a ruby noob, so...)
>>
> 
> There is probably a cleaner way to do this but...
> 
> sorted_keys = @my_hash.keys.sort do |a,b|
>   next result unless res=(@my_hash[a]['name']<=>@my_hash[b]['name']) == 0
>   @my_hash[a]['sort_date']<=>@my_hash[b]['sort_date']
> end

That should be:

sorted_keys = @my_hash.keys.sort do |a,b|
   next result unless result=(@my_hash[a]['name']<=>@my_hash[b]['name']) == 0
   @my_hash[a]['sort_date']<=>@my_hash[b]['sort_date']
end