From: Robert Dober <robert.dober@...>
Date: 2007-08-02T01:33:58+09:00
Subject: Re: count : array to array of hashes

On 8/1/07, Jean-S�bastien <jeansebastien.ney@gmail.com> wrote:
> Hi,
>   I'm tryind to count distinct ids from an array (array_of_ids =
> [1,2,3,1,2]), and want a result array of hashes looking like it :
> result = [{;id=>1,:count=>2},{;id=>2,:count=>2},{;id=>3,:count=>1}]
>
> i tried it, but it always returns errors :
> result = array_of_ids.inject(Array.new){ |a,x| elt = a.find{|h| h[:id]
> == x} || {:id => x, :count => 0}; elt[:count] += 1; elt}
>
> i took my information from this post :
> http://groups.google.com/group/comp.lang.ruby/browse_thread/thread/3122212f6db8d7f5/04a7b10da8195cec?lnk=gst&q=array++count&rnum=8#04a7b10da8195cec
>
> If someone could help.
>
> regards
>
>
>
irb(main):005:0> a=[1,2,3,42,2,2,3]
=> [1, 2, 3, 42, 2, 2, 3]
irb(main):006:0> a.inject([]){|r,ele| r[ele][:count]+=1 rescue
r[ele]={:id => ele, :count=>1}; r}.compact
=> [{:count=>1, :id=>1}, {:count=>3, :id=>2}, {:count=>2, :id=>3},
{:count=>1, :id=>42}]
irb(main):007:0>

HTH
Robert



-- 
[...] as simple as possible, but no simpler.
-- Attributed to Albert Einstein