public static IEnumerable<Coordinate> ApproximateTrajectoryPartition(Trajectory trajectory)
{
var characteristicPoints = new List<Coordinate> ();
characteristicPoints.Add (trajectory.Coordinates.First ());
int startIndex = 0;
int length = 0;
while (startIndex + length < trajectory.Count) {
int currentIndex = startIndex + length;
int costPar = minimumDescriptionLengthPar (trajectory, startIndex, currentIndex);
int costNoPar = minimumDescriptionLengthNoPar (trajectory, startIndex, currentIndex);
if (costPar > costNoPar) {
characteristicPoints.Add (trajectory.Coordinates.ElementAt (currentIndex - 1));
startIndex = currentIndex - 1;
length = 1;
} else {
length++;
}
}
cw++;
Console.WriteLine("Progress: Trajectory " + cw + "/100000");
return characteristicPoints;
}
public static Trajectory ParseTrajectory(String polyline)
{
var trajectory = new Trajectory();
var sep = new char[] { ']' };
var split = polyline.Split(sep, options:StringSplitOptions.RemoveEmptyEntries);
IEnumerable<string> points = split.Take(split.Count() - 1).Select(p => p.Remove(0, 3));
foreach(var point in points) {
var coordinate = ParseCoordinate (point);
if (trajectory.Coordinates.LastOrDefault () == null || isFarEnough (trajectory.Coordinates.LastOrDefault (), coordinate)) {
trajectory.Add (coordinate);
}
}
return trajectory;
}
public static int minimumDescriptionLengthNoPar(Trajectory trajectory, int startIndex, int endIndex)
{
return descriptionCost (trajectory, startIndex, endIndex);
}
private static int encodingCost(Trajectory trajectory, int startIndex, int endIndex)
{
double perpendicularDist;
double angleDist;
int encodingCost = 0;
Coordinate startComponent = trajectory.Coordinates.ElementAt (startIndex);
Coordinate endComponent = trajectory.Coordinates.ElementAt (endIndex);
//TODO correct this
if(startComponent.Vector == endComponent.Vector) return 0;
for (int i = startIndex; i < endIndex; i++) {
Coordinate startSegment = trajectory.Coordinates.ElementAt (i);
Coordinate endSegment = trajectory.Coordinates.ElementAt (i + 1);
perpendicularDist = perpendicularDistance(startComponent, endComponent, startSegment, endSegment);
angleDist = angleDistance(startComponent, endComponent, startSegment, endSegment);
if (perpendicularDist< 1.0)
perpendicularDist = 1.0f;
if (angleDist < 1.0)
angleDist = 1.0f;
encodingCost += (int)Math.Ceiling(Math.Log(perpendicularDist, 2)) +
(int)Math.Ceiling(Math.Log(angleDist, 2));
}
return encodingCost;
}
private static int descriptionCost(Trajectory trajectory, int startIndex, int endIndex)
{
Coordinate startSegment = trajectory.Coordinates.ElementAt (startIndex);
Coordinate endSegment = trajectory.Coordinates.ElementAt (endIndex);
double distance = euclidianDistance (startSegment.Vector, endSegment.Vector);
if (distance < 1.0)
distance = 1.0f;
return (int)Math.Ceiling (Math.Log (distance, 2));
}
