From: Dave Thomas <dave@...>
Date: 2003-07-05T13:20:35+09:00
Subject: Re: Ruby Code Snippet: Array.count

Stefan Arentz wrote:

> Maybe this functionality is already somewhere in Ruby, but I could not
> find it. This little snippet extends Array with a count method. It takes
> a code block that can be used to count elements that match a specific
> condition:
> 
>  a = Array[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>  puts a.count { |v| v < 5 }
> 
>   ==> 4
> 
> The code:
> 
>  class Array
>    def count(&action)
>      count = 0
>      self.each { |v| count = count + 1 if action.call(v) }
>      return count
>    end
>  end

I'm starting to like using 'inject' for this kind of thing, but it isn't 
as clear to read:

   class Array
     def count
       inject(0) {|sum, e| yield(e) ? sum + 1 : sum }
     end
   end

> Ruby is sweet :-)


Agreed :)


Cheers


Dave