duration_for

gistfile1.rb

#!/usr/bin/env ruby

def duration_for spec
   ret = nil
   if((m = %r/^ (\d+(?:\.\d+)?) : (\d+(?:\.\d+)?) : (\d+(?:\.\d+)?) $/iox.match(spec.to_s)))
     m, h, m, s, ignored = m.to_a
     h, m, s = Float(h), Float(m), Float(s)
     ret = (h * 60 * 60) + (m * 60) + (s)
   else
     pat = %r/(\d+(?:\.\d+)?)\s*([sSmMhHdDwWyY][^\d]*)?/
     begin
       "#{ spec }".scan(pat) do |m|
         n = Float m[0]
         unit = m[1]
         if unit
           factor =
             case unit
               when %r/^m/i
                 case unit
                   when %r/^mo/i
                     7 * (60 * 60 * 24)
                   else
                     60
                 end
               when %r/^h/i
                 60 * 60
               when %r/^d/i
                 60 * 60 * 24
               when %r/^w/i
                 7 * (60 * 60 * 24)
               when %r/^y/i
                 365 * 7 * (60 * 60 * 24)
               else
                 1
             end
           n *= factor
         end
         ret ||= 0.0
         ret += n
       end
     rescue
       raise "bad time spec <#{ spec }>"
     end
   end
   ret
end

p duration_for('1 minute')
p duration_for('1 hour and 1 minute')
p duration_for('6 days, 3 hours and 1 minute')
p duration_for('1 month, 6 days, 3 hours and 2 minutes')

Found this here: http://www.ruby-forum.com/topic/166915