Question

I have an array of hashes. Each hash has an uses key. Multiple hashes can share the same uses value.

[{uses => 0},{uses => 1},{uses => 2},{uses => 1},{uses => 0},{uses => 1},{uses => 3}]

How can I generate an array of the most frequent uses values, in a descending order?

[1,0,2,3]

Answer 1

Referencing this discussion of frequency of items in a list, we can easily modify this for your task.

> unsorted = [{:uses=>0}, {:uses=>1}, {:uses=>2}, {:uses=>1}, {:uses=>0}, {:uses=>1}, {:uses=>3}].map{|h| h[:uses]}
> sorted = unsorted.uniq.sort_by{|u| unsorted.grep(u).size}.reverse
 => [1, 0, 2, 3]