org.opentripplanner.streets

Class LinkedPointSet

java.lang.Object

org.opentripplanner.streets.LinkedPointSet

public class LinkedPointSet
extends Object

A LinkedPointSet is a PointSet that has been pre-connected to a StreetLayer in a non-destructive, reversible way. This is a replacement for SampleSet. It is a column store of locations that have not been permanently spliced into the graph. We cannot just adapt the SampleSet constructor because it holds on to OTP Vertex objects. In the new system we have only vertex indexes. Well, there are Vertex cursor objects but we're not going to save those. Likewise for TimeSurfaces which are intersected with SampleSets. They are keyed on Vertex references so need to be replaced. Semi-obsolete notes: Note that we don't ever need to traverse into a temporary vertex, only out of one, so temporary vertices do not interfere at all with the permanent graph. A temp vertex set can be used for a big set of vertices, but also for single origin and target vertices in point to point searches. Temp vertex sets can be persisted in the graph itself to save a worker the effort of loading street geometries and re-linking stops. We can't use TempVertexSets to handle linking transit stops into the street network, because we want other TempVertexSets to see the transit stop splitters as permanent and insert themselves between the intersection and the transit stop splitter vertex. Searches always proceed outward from origins or targets (think StopTreeCache for the targets, which handles the last mile from transit to targets). We can have completely temporary vertices that are not even recorded in the main transport network store. Keep in mind that if origins and destinations are pre-linked into the graph, the street geometries or even the whole street layer can be dropped entirely, and it’s still useful for routing. So the TransportNetwork must be serializable and usable with a null StreetLayer.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	LinkedPointSet.TravelTimeFunction A functional interface for fetching the travel time to any street vertex in the transport network.

Field Summary

Fields

Modifier and Type	Field and Description
PointSet	pointSet LinkedPointSets are long-lived and not extremely numerous, so we keep references to the objects it was built from.
List<int[]>	stopTrees
StreetLayer	streetLayer We need to retain the street layer so we can look up edge endpoint vertices for the edge IDs.

Constructor Summary

Constructors

Constructor and Description
LinkedPointSet(PointSet pointSet, StreetLayer streetLayer) A LinkedPointSet is a PointSet that has been pre-connected to a StreetLayer in a non-destructive, reversible way.

Method Summary

Modifier and Type	Method and Description
PointSetTimes	eval(LinkedPointSet.TravelTimeFunction travelTimeForVertex) Determine the travel time to every temporary vertex in this set.
void	makeStopTrees() Makes one stop tree for each transit stop in the associated TransportNetwork.
int	size()

Methods inherited from class java.lang.Object

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

Field Detail

pointSet

public final PointSet pointSet

LinkedPointSets are long-lived and not extremely numerous, so we keep references to the objects it was built from. Besides these fields are useful for later processing of LinkedPointSets.

streetLayer

public final StreetLayer streetLayer

We need to retain the street layer so we can look up edge endpoint vertices for the edge IDs. Besides, this object is inextricably linked to one street network.

stopTrees

public transient List<int[]> stopTrees

Constructor Detail

LinkedPointSet

public LinkedPointSet(PointSet pointSet,
                      StreetLayer streetLayer)

A LinkedPointSet is a PointSet that has been pre-connected to a StreetLayer in a non-destructive, reversible way. These objects are long-lived and not extremely numerous, so we keep references to the objects it was built from. Besides they are useful for later processing of LinkedPointSets.

Method Detail

size

public int size()

eval

public PointSetTimes eval(LinkedPointSet.TravelTimeFunction travelTimeForVertex)

Determine the travel time to every temporary vertex in this set. The parameter is a function from street vertex indexes to elapsed travel times. TODO: Departure times and walking speeds should be supplied.

Returns:

a list of travel times to each point in the PointSet. Integer.MAX_VALUE means a vertex was unreachable.

makeStopTrees

public void makeStopTrees()

Makes one stop tree for each transit stop in the associated TransportNetwork. They are stored in the LinkedPointSet because it provides enough context: points, streets, and transit together. The street later linked to this PointSet must already be associated with a transit layer. It is a bad idea to serialize the trees, that makes the serialized graph about 3x bigger. The packed format does not make the serialized size any smaller (the Trove serializers are already smart). However the packed representation uses less live memory: 665 vs 409 MB (including all other data) on Portland. At one point we experimented with doing the entire search here from all transit stops all the way up to the points. However that takes too long when switching pointsets. So we precache distances to all street vertices, and then just extend that to points.