pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / spatial / src / java / org / apache / lucene / spatial / tier / DistanceHandler.java

diff --git a/lucene-java-3.5.0/lucene/contrib/spatial/src/java/org/apache/lucene/spatial/tier/DistanceHandler.java b/lucene-java-3.5.0/lucene/contrib/spatial/src/java/org/apache/lucene/spatial/tier/DistanceHandler.java
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+++ b/lucene-java-3.5.0/lucene/contrib/spatial/src/java/org/apache/lucene/spatial/tier/DistanceHandler.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.tier;
+
+import org.apache.lucene.spatial.DistanceUtils;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Provide a high level access point to distances
+ * Used by DistanceSortSource and DistanceQuery
+ *  
+ * <p><font color="red"><b>NOTE:</b> This API is still in
+ * flux and might change in incompatible ways in the next
+ * release.</font>
+ *
+ */
+public class DistanceHandler {
+
+  public enum Precision {EXACT, TWOFEET, TWENTYFEET, TWOHUNDREDFEET}
+  
+  private Map<Integer,Double> distances;
+  private Map<String, Double> distanceLookupCache;
+  private Precision precise;
+  
+  public DistanceHandler (Map<Integer,Double> distances, Map<String, Double> distanceLookupCache, Precision precise){
+    this.distances = distances;
+    this.distanceLookupCache = distanceLookupCache;
+    this.precise = precise; 
+  }
+  
+  
+  public static double getPrecision(double x, Precision thisPrecise){
+    
+    if(thisPrecise != null){
+      double dif = 0;
+      switch(thisPrecise) {
+        case EXACT: return x;
+        case TWOFEET:        dif = x % 0.0001; break;
+        case TWENTYFEET:     dif = x % 0.001;  break;
+        case TWOHUNDREDFEET: dif = x % 0.01; break;
+      }
+      return x - dif;
+    }
+    return x;
+  }
+  
+  public Precision getPrecision() {
+    return precise;
+  }
+  
+  public double getDistance(int docid, double centerLat, double centerLng, double lat, double lng){
+  
+    // check to see if we have distances
+    // if not calculate the distance
+    if(distances == null){
+      return DistanceUtils.getDistanceMi(centerLat, centerLng, lat, lng);
+    }
+    
+    // check to see if the doc id has a cached distance
+    Double docd = distances.get( docid );
+    if (docd != null){
+      return docd.doubleValue();
+    }
+    
+    //check to see if we have a precision code
+    // and if another lat/long has been calculated at
+    // that rounded location
+    if (precise != null) {
+      double xLat = getPrecision(lat, precise);
+      double xLng = getPrecision(lng, precise);
+      
+      String k = Double.valueOf(xLat).toString() +","+ Double.valueOf(xLng).toString();
+    
+      Double d = (distanceLookupCache.get(k));
+      if (d != null){
+        return d.doubleValue();
+      }
+    }
+    
+    //all else fails calculate the distances    
+    return DistanceUtils.getDistanceMi(centerLat, centerLng, lat, lng);
+  }
+  
+  
+  public static void main(String args[]){ 
+    DistanceHandler db = new DistanceHandler(new HashMap<Integer,Double>(), new HashMap<String,Double>(), Precision.TWOHUNDREDFEET);
+    System.out.println(DistanceHandler.getPrecision(-1234.123456789, db.getPrecision()));
+  }
+}