From: Rob Biedenharn <Rob@...>
Date: 2010-03-26T02:42:39+09:00
Subject: Re: problem sorting

Since no one has duplicated what you seemed to be trying:

On Mar 25, 2010, at 11:31 AM, Jesús Gabriel y Galán wrote:
> On Thu, Mar 25, 2010 at 3:58 PM, Augusto Garcia <augus1@umbc.edu>  
> wrote:
>> I am trying to sort an array using a block but somehow I am not  
>> seeing
>> what I am want. First I want to sort the total, then break the tie on
>> gold goldcount, silvercount and finally on bronzcount
>>
>> Here is my code. what am I missing? please help
>>
>>  # compare and order by totals
>>        result = b[:total] <=> a[:total]
>>        # if tied, break the number of gold medals
>>        result != 0 ? result : b[:goldcount] <=> a[:goldcount]
>>        result != 0 ? result : b[:silvercount] <=> a[:silvercount]
>>        result != 0 ? result : b[:bronzcount] <=> a[:bronzcount]
>>        result != 0 ? result : b[:country] <=> a[:country]
>>  end
>

   .sort {|a,b|
     (b[:total] <=> a[:total]).nonzero? ||
     (b[:goldcount] <=> a[:goldcount]).nonzero? ||
     (b[:silvercount] <=> a[:silvercount]).nonzero? ||
     (b[:bronzcount] <=> a[:bronzcount]).nonzero? ||
     b[:country] <=> a[:country]
   }

Look at what Numeric#nonzero? is meant for ;-)

Also, your original breaks the final tie by reverse sort of the  
country so I do here as well. Augusto has an ascending sort on all and  
Jesús just has an ascending sort on the country.

-Rob

> I assume you have an array of hashes:
>
> irb(main):001:0> country_medals = []
> => []
>
> irb(main):002:0> country_medals << {:country => "Spain", :total =>
> 100, :goldcount => 100, :silvercount => 0, :bronzecount => 0}
> => [{:country=>"Spain", :total=>100, :goldcount=>100, :silvercount=>0,
> :bronzecount=>0}]
>
> irb(main):003:0> country_medals << {:country => "US", :total => 50,
> :goldcount => 50, :silvercount => 0, :bronzecount => 0}
> => [{:country=>"Spain", :total=>100, :goldcount=>100, :silvercount=>0,
> :bronzecount=>0}, {:country=>"US", :total=>50, :goldcount=>50,
> :silvercount=>0, :bronzecount=>0}]
>
> irb(main):004:0> country_medals << {:country => "UK", :total => 50,
> :goldcount => 45, :silvercount => 5, :bronzecount => 0}
> => [{:country=>"Spain", :total=>100, :goldcount=>100, :silvercount=>0,
> :bronzecount=>0}, {:country=>"US", :total=>50, :goldcount=>50,
> :silvercount=>0, :bronzecount=>0}, {:country=>"UK", :total=>50,
> :goldcount=>45, :silvercount=>5, :bronzecount=>0}]
>
> irb(main):010:0> country_medals.sort_by {|x| [-x[:total],
> -x[:goldcount], -x[:silvercount], -x[:bronzecount], x[:country]]}
> => [{:country=>"Spain", :total=>100, :goldcount=>100, :silvercount=>0,
> :bronzecount=>0}, {:country=>"US", :total=>50, :goldcount=>50,
> :silvercount=>0, :bronzecount=>0}, {:country=>"UK", :total=>50,
> :goldcount=>45, :silvercount=>5, :bronzecount=>0}]
>
>
> Jesus.
>

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com