package aima.core.environment.map;
import java.util.Collections;
import java.util.Hashtable;
import java.util.List;
import aima.core.util.Util;
import aima.core.util.datastructure.LabeledGraph;
import aima.core.util.datastructure.Point2D;
/**
* Implements a map with locations, distance labeled links between the
* locations, straight line distances, and 2d-placement positions of locations.
* Locations are represented by strings and travel distances by double values.
* Locations and links can be added dynamically and removed after creation. This
* enables to read maps from file or to modify them with respect to newly
* obtained knowledge.
*
* @author Ruediger Lunde
*/
public class ExtendableMap implements Map {
/**
* Stores map data. Locations are represented as vertices and connections
* (links) as directed edges labeled with corresponding travel distances.
*/
private final LabeledGraph<String, Double> links;
/** Stores xy-coordinates for each location. */
private final Hashtable<String, Point2D> locationPositions;
/** Creates an empty map. */
public ExtendableMap() {
links = new LabeledGraph<String, Double>();
locationPositions = new Hashtable<String, Point2D>();
}
/** Removes everything. */
public void clear() {
links.clear();
locationPositions.clear();
}
/** Clears all connections but keeps location position informations. */
public void clearLinks() {
links.clear();
}
/** Returns a list of all locations. */
public List<String> getLocations() {
return links.getVertexLabels();
}
/** Checks whether the given string is the name of a location. */
public boolean isLocation(String str) {
return links.isVertexLabel(str);
}
/**
* Answers to the question: Where can I get, following one of the
* connections starting at the specified location?
*/
public List<String> getLocationsLinkedTo(String fromLocation) {
List<String> result = links.getSuccessors(fromLocation);
Collections.sort(result);
return result;
}
/**
* Returns the travel distance between the two specified locations if they
* are linked by a connection and null otherwise.
*/
public Double getDistance(String fromLocation, String toLocation) {
return links.get(fromLocation, toLocation);
}
/** Adds a one-way connection to the map. */
public void addUnidirectionalLink(String fromLocation, String toLocation,
Double distance) {
links.set(fromLocation, toLocation, distance);
}
/**
* Adds a connection which can be traveled in both direction. Internally,
* such a connection is represented as two one-way connections.
*/
public void addBidirectionalLink(String fromLocation, String toLocation,
Double distance) {
links.set(fromLocation, toLocation, distance);
links.set(toLocation, fromLocation, distance);
}
/**
* Returns a location which is selected by random.
*/
public String randomlyGenerateDestination() {
return Util.selectRandomlyFromList(getLocations());
}
/** Removes a one-way connection. */
public void removeUnidirectionalLink(String fromLocation, String toLocation) {
links.remove(fromLocation, toLocation);
}
/** Removes the two corresponding one-way connections. */
public void removeBidirectionalLink(String fromLocation, String toLocation) {
links.remove(fromLocation, toLocation);
links.remove(toLocation, fromLocation);
}
/**
* Defines the position of a location as with respect to an orthogonal
* coordinate system.
*/
public void setPosition(String loc, double x, double y) {
locationPositions.put(loc, new Point2D(x, y));
}
/**
* Defines the position of a location within the map. Using this method, one
* location should be selected as reference position (<code>dist=0</code>
* and <code>dir=0</code>) and all the other location should be placed
* relative to it.
*
* @param loc
* location name
* @param dist
* distance to a reference position
* @param dir
* bearing (compass direction) in which the location is seen from
* the reference position
*/
public void setDistAndDirToRefLocation(String loc, double dist, int dir) {
Point2D coords = new Point2D(-Math.sin(dir * Math.PI / 180.0) * dist,
Math.cos(dir * Math.PI / 180.0) * dist);
links.addVertex(loc);
locationPositions.put(loc, coords);
}
/**
* Returns the position of the specified location as with respect to an
* orthogonal coordinate system.
*/
public Point2D getPosition(String loc) {
return locationPositions.get(loc);
}
}