simple way to calculate time duration based on ruby-duration

time_duration.rb

# start  = Time.now
# sleep 20
# finish = Time.now
# calc(finish - start) => [0, 0, 0, 0, 20]
# [weeks, days, hours, minutes, seconds]
#
def calc(seconds)
  #        weeks   days   hours min s 
  mul    = [604800, 86400, 3600, 60, 1]
  values = [:weeks, :days, :hours, :minutes, :seconds]
  units  = []
  total  = seconds.to_f.round
  mul.inject(total) do |t, m|
    units << t / m
    t % m
  end
  Hash[values.zip(units)]
end