Mercurial > dive4elements > gnv-client
comparison gnv-artifacts/src/main/java/de/intevation/gnv/math/L1Comparator.java @ 805:bb7afd783321
Removed trailing whitespace. Added more javadoc.
gnv-artifacts/trunk@887 c6561f87-3c4e-4783-a992-168aeb5c3f6f
| author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
|---|---|
| date | Thu, 08 Apr 2010 11:31:44 +0000 |
| parents | 6cff63d0c434 |
| children | a645bd23c1c8 |
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| 804:9058c08eac3a | 805:bb7afd783321 |
|---|---|
| 3 import com.vividsolutions.jts.geom.Coordinate; | 3 import com.vividsolutions.jts.geom.Coordinate; |
| 4 | 4 |
| 5 import java.util.Comparator; | 5 import java.util.Comparator; |
| 6 | 6 |
| 7 /** | 7 /** |
| 8 * Compares two coordinates a and b by their L1(Matnhattan) distance | |
| 9 * relative to a reference point r. | |
| 10 * da = L1(a, r)<br> | |
| 11 * db = L1(b, r)<br> | |
| 12 * -1 if da < db, +1 if da > db, 0 else. | |
| 8 * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a> | 13 * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a> |
| 9 */ | 14 */ |
| 10 public class L1Comparator | 15 public class L1Comparator |
| 11 implements Comparator | 16 implements Comparator |
| 12 { | 17 { |
| 13 private Coordinate ref; | 18 private Coordinate ref; |
| 14 | 19 |
| 20 /** | |
| 21 * Default constructor. | |
| 22 */ | |
| 15 public L1Comparator() { | 23 public L1Comparator() { |
| 16 } | 24 } |
| 17 | 25 |
| 26 /** | |
| 27 * Constructor to create a L1Comparator with a given reference point. | |
| 28 * @param ref The reference point. | |
| 29 */ | |
| 18 public L1Comparator(Coordinate ref) { | 30 public L1Comparator(Coordinate ref) { |
| 19 this.ref = ref; | 31 this.ref = ref; |
| 20 } | 32 } |
| 21 | 33 |
| 34 /** | |
| 35 * Explicitly sets the reference point. | |
| 36 * @param ref The reference point. | |
| 37 */ | |
| 22 public void setReference(Coordinate ref) { | 38 public void setReference(Coordinate ref) { |
| 23 this.ref = ref; | 39 this.ref = ref; |
| 24 } | 40 } |
| 25 | 41 |
| 42 /** | |
| 43 * Compares to coordinate by their L1 distance to the reference point. | |
| 44 * @param a The first coordinate. | |
| 45 * @param b The second coordinate. | |
| 46 * @return -1 if L1(a, ref) < L1(b, ref), | |
| 47 * +1 if L1(a, ref) > L1(b, ref), 0 else. | |
| 48 */ | |
| 26 public int compare(Object a, Object b) { | 49 public int compare(Object a, Object b) { |
| 27 Coordinate pa = (Coordinate)a; | 50 Coordinate pa = (Coordinate)a; |
| 28 Coordinate pb = (Coordinate)b; | 51 Coordinate pb = (Coordinate)b; |
| 29 double da = L1(ref, pa); | 52 double da = L1(ref, pa); |
| 30 double db = L1(ref, pb); | 53 double db = L1(ref, pb); |
| 31 if (da < db) return -1; | 54 if (da < db) return -1; |
| 32 if (da > db) return +1; | 55 if (da > db) return +1; |
| 33 return 0; | 56 return 0; |
| 34 } | 57 } |
| 35 | 58 |
| 59 /** | |
| 60 * Computes the L1 distance between two points a and b:<br> | |
| 61 * L1(a, b) = abs(a.x - b.x) + abs(a.y - b.y) | |
| 62 * @param a The first point. | |
| 63 * @param b The second point. | |
| 64 * @return The L1 distance. | |
| 65 */ | |
| 36 public static double L1(Coordinate a, Coordinate b) { | 66 public static double L1(Coordinate a, Coordinate b) { |
| 37 return Math.abs(a.x - b.x) + Math.abs(a.y - b.y); | 67 return Math.abs(a.x - b.x) + Math.abs(a.y - b.y); |
| 38 } | 68 } |
| 39 | |
| 40 } | 69 } |
| 41 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : | 70 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |