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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.geo;
import com.yahoo.api.annotations.Beta;
/**
* Utility for parsing a geographical distance with unit.
*/
@Beta
public class DistanceParser {
// according to wikipedia:
// Earth's equatorial radius = 6378137 meter - not used
// meters per mile = 1609.344
// 180 degrees equals one half diameter equals PI*r
// Earth's polar radius = 6356752 meter
public final static double m2deg = 180.0 / (Math.PI * 6356752.0);
public final static double km2deg = 1000.000 * 180.0 / (Math.PI * 6356752.0);
public final static double mi2deg = 1609.344 * 180.0 / (Math.PI * 6356752.0);
private final double degrees;
public double getDegrees() { return degrees; }
/**
* Parse a distance in some kind of units, converting to geographical degrees.
* Note that the number and the unit should be separated by a single space only,
* or not separated at all.
* Supported units are "m", "km", "miles", and "deg",
* the last one meaning degrees with no conversion.
* For brevity "mi" = "miles" and "d" = "deg".
**/
static public double parse(String distance) {
var parser = new DistanceParser(distance, false);
return parser.degrees;
}
DistanceParser(String distance, boolean assumeMicroDegrees) {
if (distance.endsWith(" km")) {
double km = Double.valueOf(distance.substring(0, distance.length()-3));
degrees = km * km2deg;
} else if (distance.endsWith(" m")) {
double meters = Double.valueOf(distance.substring(0, distance.length()-2));
degrees = meters * m2deg;
} else if (distance.endsWith(" miles")) {
double miles = Double.valueOf(distance.substring(0, distance.length()-6));
degrees = miles * mi2deg;
} else if (distance.endsWith(" mi")) {
double miles = Double.valueOf(distance.substring(0, distance.length()-3));
degrees = miles * mi2deg;
} else if (distance.endsWith(" deg")) {
degrees = Double.valueOf(distance.substring(0, distance.length()-4));
} else if (distance.endsWith(" d")) {
degrees = Double.valueOf(distance.substring(0, distance.length()-2));
} else if (distance.endsWith("km")) {
double km = Double.valueOf(distance.substring(0, distance.length()-2));
degrees = km * km2deg;
} else if (distance.endsWith("m")) {
double meters = Double.valueOf(distance.substring(0, distance.length()-1));
degrees = meters * m2deg;
} else if (distance.endsWith("miles")) {
double miles = Double.valueOf(distance.substring(0, distance.length()-5));
degrees = miles * mi2deg;
} else if (distance.endsWith("mi")) {
double miles = Double.valueOf(distance.substring(0, distance.length()-2));
degrees = miles * mi2deg;
} else if (distance.endsWith("deg")) {
degrees = Double.valueOf(distance.substring(0, distance.length()-3));
} else if (distance.endsWith("d")) {
degrees = Double.valueOf(distance.substring(0, distance.length()-1));
} else if (assumeMicroDegrees) {
degrees = Integer.parseInt(distance) * 0.000001;
} else {
throw new IllegalArgumentException("missing unit for distance: "+distance);
}
}
}
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