/// <summary>
/// Searches for the closest stop.
/// </summary>
/// <returns></returns>
public static uint SearchClosest(this StopsDb.Enumerator stopsDbEnumerator, float latitude, float longitude,
float offset)
{
// search for all nearby stops.
var stops = Hilbert.Search(stopsDbEnumerator, latitude, longitude, offset);
var bestDistance = double.MaxValue;
var bestVertex = Constants.NoStopId;
foreach (var stop in stops)
{
if (stopsDbEnumerator.MoveTo(stop))
{
var lat = stopsDbEnumerator.Latitude;
var lon = stopsDbEnumerator.Longitude;
var distance = Coordinate.DistanceEstimateInMeter(latitude, longitude, lat, lon);
if (distance < bestDistance)
{ // a new closest vertex found.
bestDistance = distance;
bestVertex = stop;
}
}
}
return(bestVertex);
}
/// <summary>
/// Searches the stops db assuming it has been sorted.
/// </summary>
public static HashSet <uint> Search(this StopsDb.Enumerator stopsDbEnumerator, int n, float minLatitude, float minLongitude,
float maxLatitude, float maxLongitude)
{
var targets = Itinero.Algorithms.Search.Hilbert.HilbertCurve.HilbertDistances(
System.Math.Max(minLatitude, -90),
System.Math.Max(minLongitude, -180),
System.Math.Min(maxLatitude, 90),
System.Math.Min(maxLongitude, 180), n);
targets.Sort();
var stops = new HashSet <uint>();
var targetIdx = 0;
var stop1 = (uint)0;
var stop2 = (uint)stopsDbEnumerator.Count - 1;
while (targetIdx < targets.Count)
{
uint stop;
int count;
if (Hilbert.Search(stopsDbEnumerator, targets[targetIdx], n, stop1, stop2, out stop, out count))
{ // the search was successful.
while (count > 0)
{ // there have been stops found.
if (stopsDbEnumerator.MoveTo((uint)stop + (uint)(count - 1)))
{ // the stop was found.
var vertexLat = stopsDbEnumerator.Latitude;
var vertexLon = stopsDbEnumerator.Longitude;
if (minLatitude < vertexLat &&
minLongitude < vertexLon &&
maxLatitude > vertexLat &&
maxLongitude > vertexLon)
{ // within offset.
stops.Add((uint)stop + (uint)(count - 1));
}
}
count--;
}
// update stop1.
stop1 = stop;
}
// move to next target.
targetIdx++;
}
return(stops);
}
/// <summary>
/// Searches the stops db for nearby stops assuming it has been sorted.
/// </summary>
public static HashSet <uint> Search(this StopsDb.Enumerator stopsDbEnumerator, float latitude, float longitude,
float offset)
{
return(Hilbert.Search(stopsDbEnumerator, Itinero.Algorithms.Search.Hilbert.HilbertExtensions.DefaultHilbertSteps, latitude - offset, longitude - offset,
latitude + offset, longitude + offset));
}
/// <summary>
/// Searches the stops db assuming it has been sorted.
/// </summary>
public static bool Search(this StopsDb.Enumerator stopsDbEnumerator, long hilbert, int n, uint stop1, uint stop2,
out uint vertex, out int count)
{
var hilbert1 = Hilbert.Distance(stopsDbEnumerator, n, stop1);
var hilbert2 = Hilbert.Distance(stopsDbEnumerator, n, stop2);
while (stop1 <= stop2)
{
// check the current hilbert distances.
if (hilbert1 > hilbert2)
{ // situation is impossible and probably the stops are not sorted.
throw new Exception("Stops not sorted: Binary search using hilbert distance not possible.");
}
if (hilbert1 == hilbert)
{ // found at hilbert1.
var lower = stop1;
while (hilbert1 == hilbert)
{
if (lower == 0)
{ // stop here, not more vertices lower.
break;
}
lower--;
hilbert1 = Hilbert.Distance(stopsDbEnumerator, n, lower);
}
var upper = stop1;
hilbert1 = Hilbert.Distance(stopsDbEnumerator, n, upper);
while (hilbert1 == hilbert)
{
if (upper >= stopsDbEnumerator.Count - 1)
{ // stop here, no more vertices higher.
break;
}
upper++;
hilbert1 = Hilbert.Distance(stopsDbEnumerator, n, upper);
}
vertex = lower;
count = (int)(upper - lower) + 1;
return(true);
}
if (hilbert2 == hilbert)
{ // found at hilbert2.
var lower = stop2;
while (hilbert2 == hilbert)
{
if (lower == 0)
{ // stop here, not more vertices lower.
break;
}
lower--;
hilbert2 = Hilbert.Distance(stopsDbEnumerator, n, lower);
}
var upper = stop2;
hilbert2 = Hilbert.Distance(stopsDbEnumerator, n, upper);
while (hilbert2 == hilbert)
{
if (upper >= stopsDbEnumerator.Count - 1)
{ // stop here, no more vertices higher.
break;
}
upper++;
hilbert2 = Hilbert.Distance(stopsDbEnumerator, n, upper);
}
vertex = lower;
count = (int)(upper - lower) + 1;
return(true);
}
if (hilbert1 == hilbert2 ||
stop1 == stop2 ||
stop1 == stop2 - 1)
{ // search is finished.
vertex = stop1;
count = 0;
return(true);
}
// Binary search: calculate hilbert distance of the middle.
var vertexMiddle = stop1 + (uint)((stop2 - stop1) / 2);
var hilbertMiddle = Hilbert.Distance(stopsDbEnumerator, n, vertexMiddle);
if (hilbert <= hilbertMiddle)
{ // target is in first part.
stop2 = vertexMiddle;
hilbert2 = hilbertMiddle;
}
else
{ // target is in the second part.
stop1 = vertexMiddle;
hilbert1 = hilbertMiddle;
}
}
vertex = stop1;
count = 0;
return(false);
}