From: Phrogz <gavin@...>
Date: 2006-10-12T12:10:07+09:00
Subject: Re: Counting Frequency of Values in an Array (And Sorting by Frequency?)

x1 wrote:
> I was able to hack it by using a hash doing various things to it.. but
> it didn't seem "rubyish".

What could be more ruby-ish than monkeypatching a built-in class and
using inject in the process?

class Array
	def counts
		inject( Hash.new(0) ){ |hash,element|
			hash[ element ] +=1
			hash
		}
	end
	def counts_up
		counts.sort_by{ |k,v| v }
	end
	def counts_down
		counts.sort_by{ |k,v| -v }
	end
end
a = ["a", "a", "a", "b", "c", "c"]
p a.counts, a.counts_up, a.counts_down
#=> {"a"=>3, "b"=>1, "c"=>2}
#=> [["b", 1], ["c", 2], ["a", 3]]
#=> [["a", 3], ["c", 2], ["b", 1]]