/* computes the distance, in meters, along a geometry */
protected static double distanceAlongGeometry(
Geometry geometry, LinearLocation startIndex, LinearLocation endIndex) {
if (endIndex == null) {
endIndex = LinearLocation.getEndLocation(geometry);
}
double total = 0;
LinearIterator it = new LinearIterator(geometry, startIndex);
LinearLocation index = startIndex;
Coordinate previousCoordinate = startIndex.getCoordinate(geometry);
it.next();
index = it.getLocation();
while (index.compareTo(endIndex) < 0) {
Coordinate thisCoordinate = index.getCoordinate(geometry);
double distance = SphericalDistanceLibrary.fastDistance(previousCoordinate, thisCoordinate);
total += distance;
previousCoordinate = thisCoordinate;
if (!it.hasNext()) break;
it.next();
index = it.getLocation();
}
// now, last bit of last segment
Coordinate finalCoordinate = endIndex.getCoordinate(geometry);
total += SphericalDistanceLibrary.distance(previousCoordinate, finalCoordinate);
return total;
}
/**
* FIXME OBA parentStation field is a string, not an AgencyAndId, so it has no agency/feed scope
* But the DC regional graph has no parent stations pre-defined, so no use dealing with them for
* now. However Trimet stops have "landmark" or Transit Center parent stations, so we don't use
* the parent stop field.
*
* <p>Ideally in the future stop clusters will replicate and/or share implementation with GTFS
* parent stations.
*
* <p>We can't use a similarity comparison, we need exact matches. This is because many street
* names differ by only one letter or number, e.g. 34th and 35th or Avenue A and Avenue B.
* Therefore normalizing the names before the comparison is essential. The agency must provide
* either parent station information or a well thought out stop naming scheme to cluster stops --
* no guessing is reasonable without that information.
*/
public void clusterStops() {
int psIdx = 0; // unique index for next parent stop
LOG.info("Clustering stops by geographic proximity and name...");
// Each stop without a cluster will greedily claim other stops without clusters.
for (Stop s0 : stopForId.values()) {
if (stopClusterForStop.containsKey(s0))
continue; // skip stops that have already been claimed by a cluster
String s0normalizedName = StopNameNormalizer.normalize(s0.getName());
StopCluster cluster = new StopCluster(String.format("C%03d", psIdx++), s0normalizedName);
// LOG.info("stop {}", s0normalizedName);
// No need to explicitly add s0 to the cluster. It will be found in the spatial index query
// below.
Envelope env = new Envelope(new Coordinate(s0.getLon(), s0.getLat()));
env.expandBy(
SphericalDistanceLibrary.metersToLonDegrees(CLUSTER_RADIUS, s0.getLat()),
SphericalDistanceLibrary.metersToDegrees(CLUSTER_RADIUS));
for (TransitStop ts1 : stopSpatialIndex.query(env)) {
Stop s1 = ts1.getStop();
double geoDistance =
SphericalDistanceLibrary.fastDistance(
s0.getLat(), s0.getLon(), s1.getLat(), s1.getLon());
if (geoDistance < CLUSTER_RADIUS) {
String s1normalizedName = StopNameNormalizer.normalize(s1.getName());
// LOG.info(" --> {}", s1normalizedName);
// LOG.info(" geodist {} stringdist {}", geoDistance, stringDistance);
if (s1normalizedName.equals(s0normalizedName)) {
// Create a bidirectional relationship between the stop and its cluster
cluster.children.add(s1);
stopClusterForStop.put(s1, cluster);
}
}
}
cluster.computeCenter();
stopClusterForId.put(cluster.id, cluster);
}
// LOG.info("Done clustering stops.");
// for (StopCluster cluster : stopClusterForId.values()) {
// LOG.info("{} at {} {}", cluster.name, cluster.lat, cluster.lon);
// for (Stop stop : cluster.children) {
// LOG.info(" {}", stop.getName());
// }
// }
}
protected static double distance(Coordinate from, Coordinate to) {
return SphericalDistanceLibrary.fastDistance(from, to);
}
