From: Simen Edvardsen <toalett@...>
Date: 2006-06-23T04:25:57+09:00
Subject: Re: Turning an Array into a Hash based on an attribute value

Disclaimer: inject is probably more appropriate, but my solution at
least looks cooler ;)

On 6/22/06, Simen Edvardsen <toalett@gmail.com> wrote:
> $ irb
> irb(main):001:0> class Array
> irb(main):002:1>   def hash_on(method)
> irb(main):003:2>
> Hash[*self.map{|m|m.send(method).to_s.to_sym}.zip(self).flatten ]
> irb(main):004:2>   end
> irb(main):005:1> end
> => nil
> irb(main):006:0> [1, "2", :three].hash_on(:class)
> => {:String=>"2", :Symbol=>:three, :Fixnum=>1}
> irb(main):007:0>
>
>
> On 6/22/06, Ashley Moran <work@ashleymoran.me.uk> wrote:
> > A guy I work with has some some work on an ActiveRecord class that
> > basically reads static lookup data, and contains (among other things)
> > an "identifier" attribute.  Given an array of all these objects he
> > wanted to access them by the contents of the identifier attribute, eg:
> >
> > data_items = DataItem.find(:all)
> > # data_items[3].identifier => "my_identifier"
> > data_items[:my_identifier].do_something # => data_items[3].do_something
> >
> > The best I can come up with is this:
> >
> >    class Array
> >      def hash_on(method)
> >        method = method.to_sym
> >        hash = { }
> >        self.each do |i|
> >          hash[i.send(method).to_s.to_sym] = i
> >        end
> >        hash
> >      end
> >    end
> >
> >    > [1, "2", :three].hash_on(:class)
> >    => {:String=>"2", :Symbol=>:three, :Fixnum=>1}
> >
> > Is there a neater (one-line?) way I missed?
> >
> > Ashley
> >
> >
>
>
> --
> - Simen
>
>


-- 
- Simen