Sorting a Ruby array based on part of a string

Question

I have the following array...

[ "global/20130102-001", "global/20131012-001, "country/uk/20121104-001" ]

I need to sort the array based on the numerical portion of the string. So the above would be sorted as:

[ "country/uk/20121104-001", "global/20130102-001", "global/20130112-001 ]

Is there a way to call .sort and ignore the first part of each element so I'm only sorting on the number?

Answer 1

Yes, there's a way. You should use a #sort_by for that. Its block is passed an array element and should return element's "sortable value". In this case, we use regex to find your string of digits (you can use another logic there, of course, like splitting on a slash).

arr = [ "global/20130102-001", "global/20131012-001", "country/uk/20121104-001" ]

arr.sort_by {|el| el.scan(/\d{8}-\d{3}/)} # => ["country/uk/20121104-001", "global/20130102-001", "global/20131012-001"]

Answer 2

Sure, just use sort_by.

  arr.sort_by do |s| 
     s.split('/').last
  end