Calculate percentage of interval covered within a given hour.

hour_intervals_from_times.rb

def hour_intervals(start_time, stop_time)
  results = Hash.new {|h,k| h[k] = Hash.new(0)}

  (start_time.to_i..stop_time.to_i).step(60).collect do |minute|
     minute_time = Time.at(minute)
     interval =  case minute_time.min
                 when (0..14) then 0
                 when (15..29) then 15
                 when (30..44) then 30
                 when (45..59) then 45
                 end

    results[minute_time.hour][interval] += 1
  end

  results
end

s = Service.last
start_time = Time.strptime("#{s.date_of_service.to_s} #{s.start_time.to_s.rjust(4,'0')}", "%Y-%m-%d %H%M")
end_time = Time.strptime("#{s.date_of_service.to_s} #{s.end_time.to_s.rjust(4,'0')}", "%Y-%m-%d %H%M")
m = hour_intervals(start_time, end_time)