113 lines
3.6 KiB
Java
113 lines
3.6 KiB
Java
/**
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* IntegerGeoPoint
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* Copyright 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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* first published 08.10.2009 on http://yacy.net
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*
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* This file is part of YaCy Content Integration
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program in the file lgpl21.txt
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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package net.yacy.cora.geo;
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/**
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* GeoPoint implementation with Integer accuracy
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*/
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public class IntegerGeoPoint implements GeoPoint {
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private final long latlon; // using one variable for the coordinate pair saves some space
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public IntegerGeoPoint(double lat, double lon) {
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this.latlon = (((long) coord2int(lat)) << 32) | (coord2int(lon));
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}
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public IntegerGeoPoint(int lat, int lon) {
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this.latlon = (((long) coord2int(lat / 1e6d)) << 32) | (coord2int(lon / 1e6d));
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}
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@Override
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public double lat() {
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return int2coord((int) (this.latlon >>> 32));
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}
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@Override
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public double lon() {
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return int2coord((int) (this.latlon & (Integer.MAX_VALUE)));
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}
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/**
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* get the implementation-dependent accuracy of the latitude
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* @return
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*/
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@Override
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public double accuracyLat() {
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return Math.abs(int2coord(1) - int2coord(2));
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}
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/**
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* get the implementation-dependent accuracy of the longitude
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* @return
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*/
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@Override
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public double accuracyLon() {
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return Math.abs(int2coord(1) - int2coord(2));
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}
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private static final double maxint = new Double(Integer.MAX_VALUE).doubleValue();
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private static final double upscale = maxint / 360.0d;
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private static final int coord2int(double coord) {
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return (int) ((coord + 180.0d) * upscale);
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}
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private static final double int2coord(int z) {
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return (z / upscale) - 180.0d;
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}
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/**
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* compute the hash code of a coordinate
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* this produces identical hash codes for locations that are close to each other
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*/
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@Override
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public int hashCode() {
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return (int) ((this.latlon & Integer.MAX_VALUE) >> 1) + (int) (this.latlon >> 33);
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}
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/**
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* equality test that is needed to use the class inside HashMap/HashSet
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*/
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@Override
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public boolean equals(final Object o) {
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if (!(o instanceof IntegerGeoPoint)) return false;
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IntegerGeoPoint oo = (IntegerGeoPoint) o;
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return (this.latlon == oo.latlon);
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}
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@Override
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public String toString() {
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return "[" + this.lat() + "," + this.lon() + "]";
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}
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public static void main(String[] args) {
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double lat = 13.419444d;
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double lon = 52.548611d;
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GeoPoint c = new IntegerGeoPoint(lat, lon);
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System.out.println(c.toString() + " #" + c.hashCode());
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System.out.println("error: lat: " + (Math.abs(c.lat() - lat) / meter) + " meter; lon: " + (Math.abs(c.lon() - lon) / meter) + " meter");
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System.out.println("accuracyLat = " + c.accuracyLat() / meter + " meter, accuracyLon = " + c.accuracyLon() / meter + " meter");
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}
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}
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