org.transitime.statistics

Class ScheduleStatistics

java.lang.Object

org.transitime.statistics.ScheduleStatistics

public class ScheduleStatistics
extends java.lang.Object

Contains methods for taking arrival/departure info that is collected in maps and processing it to determine optimal schedule.

Once all of the arrival and departure times have been processed into a map statistics is used to determine which is the best arrival/departure for the stop_times output. The goal is to use a time such that only the a desired fraction of arrivals/departures will be early. For example, if you want only 20% of the vehicle to be early with respect to the schedule time, which is reasonable because for passengers it is better for vehicles to be late rather then early so they don't miss the vehicle, then the value should be 0.2. This desiredFractionEarly value is specified when the ScheduleDataProcessor object is constructed.

The way the software tries to achieve the desiredFractionEarly is by assuming there is a Gaussian distribution of the times. By using the standard deviation of a Gaussian distribution the software estimates the value to use to such that desiredFractionEarly will be attained. Of course the distribution is not truly Gaussian. Therefore several iterations are used to adjust the value in order to get the desired results.

Note: convenient website for determining standard deviation is at http://www.mathsisfun.com/data/standard-deviation-calculator.html

Author:

SkiBu Smith

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ScheduleStatistics.Stats For containing the results of processing AVL based arrival/departure times as part of determining more accurate schedule times.

Constructor Summary

Constructors

Constructor and Description
ScheduleStatistics()

Method Summary

Modifier and Type	Method and Description
static void	determineStatsForRoute(java.util.Map<ScheduleDataProcessor.TripStopKey,GtfsStopTime> originalGtfsStopTimes, java.util.Map<ScheduleDataProcessor.TripStopKey,java.util.List<java.lang.Integer>> timesFromDbByTripStopForRouteSubMap, java.util.Map<ScheduleDataProcessor.TripStopKey,ScheduleStatistics.Stats> statsResultsByTripStopMap, java.lang.String routeId, int allowableDifferenceFromMeanSecs, int allowableDifferenceFromOriginalTimeSecs, double desiredFractionEarly, ArrivalDeparture.ArrivalsOrDepartures arrivalsOrDepartures) For the route specified first determines the basic stats including the mean and standard deviation.
static void	processScheduleAdherence(java.util.Map<ScheduleDataProcessor.TripStopKey,GtfsStopTime> gtfsStopTimes, java.util.Map<ScheduleDataProcessor.TripStopKey,ScheduleStatistics.Stats> arrivalStatsResultsByTripStopMap, java.util.Map<ScheduleDataProcessor.TripStopKey,ScheduleStatistics.Stats> departureStatsResultsByTripStopMap, int allowableEarlySecs, int allowableLateSecs) Determines and logs schedule adherence results both using the original schedule and using the new improved schedule.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ScheduleStatistics

public ScheduleStatistics()

Method Detail

determineStatsForRoute

public static void determineStatsForRoute(java.util.Map<ScheduleDataProcessor.TripStopKey,GtfsStopTime> originalGtfsStopTimes,
                                          java.util.Map<ScheduleDataProcessor.TripStopKey,java.util.List<java.lang.Integer>> timesFromDbByTripStopForRouteSubMap,
                                          java.util.Map<ScheduleDataProcessor.TripStopKey,ScheduleStatistics.Stats> statsResultsByTripStopMap,
                                          java.lang.String routeId,
                                          int allowableDifferenceFromMeanSecs,
                                          int allowableDifferenceFromOriginalTimeSecs,
                                          double desiredFractionEarly,
                                          ArrivalDeparture.ArrivalsOrDepartures arrivalsOrDepartures)

For the route specified first determines the basic stats including the mean and standard deviation. Then determines how many standard deviations to use for this route such that get approximately the desired fraction of times being earlier than the mean minus the number of standard deviations for this trip/stop. Puts the resulting Stats objects that now contain the best arrival/departure value to use into statsResultsByTripStopMap. This is done on a per route basis since it is expected that the distribution of the stats will vary between routes.

Parameters:

originalGtfsStopTimes - original data from stop_times.txt file so that can filter out outliers. Can be null for testing. Map is keyed on trip/stops and contains GtfsStopTimes.

timesFromDbByTripStopForRouteSubMap - the arrival/departure times for the route

statsResultsByTripStopMap - for returning the results

routeId - for logging

allowableDifferenceFromMeanSecs - Specifies how consistent arrival/departure times from Db must be in order to be used.

allowableDifferenceFromOriginalTimeSecs - Specifies how consistent arrival/departure times from Db must be in order to be used.

desiredFractionEarly - Specifies the desired number of the arrival times that should be early

arrivalsOrDepartures - specifies whether should handle as arrivals or departures

processScheduleAdherence

public static void processScheduleAdherence(java.util.Map<ScheduleDataProcessor.TripStopKey,GtfsStopTime> gtfsStopTimes,
                                            java.util.Map<ScheduleDataProcessor.TripStopKey,ScheduleStatistics.Stats> arrivalStatsResultsByTripStopMap,
                                            java.util.Map<ScheduleDataProcessor.TripStopKey,ScheduleStatistics.Stats> departureStatsResultsByTripStopMap,
                                            int allowableEarlySecs,
                                            int allowableLateSecs)

Determines and logs schedule adherence results both using the original schedule and using the new improved schedule.

Parameters:

gtfsStopTimes - The original GtfsStopTimes read from stop_times.txt.

arrivalStatsResultsByTripStopMap - All the arrival time results. Keyed on trip/stop.

departureStatsResultsByTripStopMap - All the departure time results. Keyed on trip/stop.

allowableEarlySecs - For schedule determining adherence

allowableLateSecs - For schedule determining adherence