001 package aima.search.map;
002
003 import java.util.Collections;
004 import java.util.Hashtable;
005 import java.util.List;
006
007 import aima.util.LabeledGraph;
008 import aima.util.Util;
009
010 /**
011 * Implements a map with locations, distance labeled links between the
012 * locations, straight line distances, and 2d-placement positions of locations.
013 * Locations are represented by strings and travel distances by integer values.
014 * Locations and links can be added dynamically and removed after creation. This
015 * enables to read maps from file or to modify them with respect to newly
016 * obtained knowledge.
017 *
018 * @author R. Lunde
019 */
020 public class ExtendableMap implements Map {
021
022 /**
023 * Stores map data. Locations are represented as vertices and connections
024 * (links) as directed edges labeled with corresponding travel distances.
025 */
026 private final LabeledGraph<String, Double> links;
027
028 /** Stores xy-coordinates for each location. */
029 private final Hashtable<String, Point2D> locationPositions;
030
031 /** Creates an empty map. */
032 public ExtendableMap() {
033 links = new LabeledGraph<String, Double>();
034 locationPositions = new Hashtable<String, Point2D>();
035 }
036
037 /** Removes everything. */
038 public void clear() {
039 links.clear();
040 locationPositions.clear();
041 }
042
043 /** Clears all connections but keeps location position informations. */
044 public void clearLinks() {
045 links.clear();
046 }
047
048 /** Returns a list of all locations. */
049 public List<String> getLocations() {
050 return links.getVertexLabels();
051 }
052
053 /** Checks whether the given string is the name of a location. */
054 public boolean isLocation(String str) {
055 return links.isVertexLabel(str);
056 }
057
058 /**
059 * Answers to the question: Where can I get, following one of the
060 * connections starting at the specified location?
061 */
062 public List<String> getLocationsLinkedTo(String fromLocation) {
063 List<String> result = links.getSuccessors(fromLocation);
064 Collections.sort(result);
065 return result;
066 }
067
068 /**
069 * Returns the travel distance between the two specified locations if they
070 * are linked by a connection and null otherwise.
071 */
072 public Double getDistance(String fromLocation, String toLocation) {
073 return links.get(fromLocation, toLocation);
074 }
075
076 /** Adds a one-way connection to the map. */
077 public void addUnidirectionalLink(String fromLocation, String toLocation,
078 Double distance) {
079 links.set(fromLocation, toLocation, distance);
080 }
081
082 /**
083 * Adds a connection which can be traveled in both direction. Internally,
084 * such a connection is represented as two one-way connections.
085 */
086 public void addBidirectionalLink(String fromLocation, String toLocation,
087 Double distance) {
088 links.set(fromLocation, toLocation, distance);
089 links.set(toLocation, fromLocation, distance);
090 }
091
092 /**
093 * Returns a location which is selected by random.
094 */
095 public String randomlyGenerateDestination() {
096 return Util.selectRandomlyFromList(getLocations());
097 }
098
099 /** Removes a one-way connection. */
100 public void removeUnidirectionalLink(String fromLocation, String toLocation) {
101 links.remove(fromLocation, toLocation);
102 }
103
104 /** Removes the two corresponding one-way connections. */
105 public void removeBidirectionalLink(String fromLocation, String toLocation) {
106 links.remove(fromLocation, toLocation);
107 links.remove(toLocation, fromLocation);
108 }
109
110 /**
111 * Defines the position of a location as with respect to an orthogonal
112 * coordinate system.
113 */
114 public void setPosition(String loc, double x, double y) {
115 locationPositions.put(loc, new Point2D(x, y));
116 }
117
118 /**
119 * Defines the position of a location within the map. Using this method, one
120 * location should be selected as reference position (<code>dist=0</code>
121 * and <code>dir=0</code>) and all the other location should be placed
122 * relative to it.
123 *
124 * @param loc
125 * location name
126 * @param dist
127 * distance to a reference position
128 * @param dir
129 * bearing (compass direction) in which the location is seen from
130 * the reference position
131 */
132 public void setDistAndDirToRefLocation(String loc, double dist, int dir) {
133 Point2D coords = new Point2D(
134 -Math.sin(dir * Math.PI / 180.0) * dist,
135 Math.cos(dir * Math.PI / 180.0) * dist);
136 links.addVertex(loc);
137 locationPositions.put(loc, coords);
138 }
139
140 /**
141 * Returns an array with two integers describing the the position of the
142 * specified location.
143 */
144 public Point2D getPosition(String loc) {
145 return locationPositions.get(loc);
146 }
147
148 }