pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / spatial / src / java / org / apache / lucene / spatial / geometry / DistanceUnits.java

diff --git a/lucene-java-3.5.0/lucene/contrib/spatial/src/java/org/apache/lucene/spatial/geometry/DistanceUnits.java b/lucene-java-3.5.0/lucene/contrib/spatial/src/java/org/apache/lucene/spatial/geometry/DistanceUnits.java
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+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.lucene.spatial.geometry;
+
+/**
+ * Enum representing difference distance units, currently only kilometers and
+ * miles
+ */
+public enum DistanceUnits {
+
+  MILES("miles", 3959, 24902),
+  KILOMETERS("km", 6371, 40076);
+
+  private static final double MILES_KILOMETRES_RATIO = 1.609344;
+
+  private final String unit;
+  
+  private final double earthCircumference;
+  
+  private final double earthRadius;
+
+  /**
+   * Creates a new DistanceUnit that represents the given unit
+   *
+   * @param unit Distance unit in String form
+   * @param earthRadius Radius of the Earth in the specific distance unit
+   * @param earthCircumfence Circumference of the Earth in the specific distance unit
+   */
+  DistanceUnits(String unit, double earthRadius, double earthCircumfence) {
+    this.unit = unit;
+    this.earthCircumference = earthCircumfence;
+    this.earthRadius = earthRadius;
+  }
+
+  /**
+   * Returns the DistanceUnit which represents the given unit
+   *
+   * @param unit Unit whose DistanceUnit should be found
+   * @return DistanceUnit representing the unit
+   * @throws IllegalArgumentException if no DistanceUnit which represents the given unit is found
+   */
+  public static DistanceUnits findDistanceUnit(String unit) {
+    if (MILES.getUnit().equalsIgnoreCase(unit) || unit.equalsIgnoreCase("mi")) {
+      return MILES;
+    }
+
+    if (KILOMETERS.getUnit().equalsIgnoreCase(unit)) {
+      return KILOMETERS;
+    }
+
+    throw new IllegalArgumentException("Unknown distance unit " + unit);
+  }
+
+  /**
+   * Converts the given distance in given DistanceUnit, to a distance in the unit represented by {@code this} 
+   *
+   * @param distance Distance to convert
+   * @param from Unit to convert the distance from
+   * @return Given distance converted to the distance in the given unit
+   */
+  public double convert(double distance, DistanceUnits from) {
+    if (from == this) {
+      return distance;
+    }
+    return (this == MILES) ? distance / MILES_KILOMETRES_RATIO : distance * MILES_KILOMETRES_RATIO;
+  }
+
+  /**
+   * Returns the string representation of the distance unit
+   *
+   * @return String representation of the distance unit
+   */
+  public String getUnit() {
+    return unit;
+  }
+  
+  /**
+   * Returns the <a href="http://en.wikipedia.org/wiki/Earth_radius">average earth radius</a>
+   *
+   * @return the average earth radius
+   */
+  public double earthRadius() {
+    return earthRadius;
+  }
+  
+  /**
+   * Returns the <a href="http://www.lyberty.com/encyc/articles/earth.html">circumference of the Earth</a>
+   * 
+   * @return  the circumference of the Earth
+   */
+  public double earthCircumference() {
+    return earthCircumference;
+  }
+}
+