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Lucene example source code file (LatLongDistanceFilter.java)

This example Lucene source code file (LatLongDistanceFilter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

distancefilter, docidset, double, double, io, ioexception, latlongdistancefilter, latlongdistancefilter, override, override, string, string

The Lucene LatLongDistanceFilter.java source code

/**
 * 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 java.io.IOException;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.FilteredDocIdSet;
import org.apache.lucene.search.FieldCache;
import org.apache.lucene.search.Filter;
import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.spatial.DistanceUtils;


/**
 * <p>NOTE: This API is still in
 * flux and might change in incompatible ways in the next
 * release.</font>
 */
public class LatLongDistanceFilter extends DistanceFilter {

  /**
   * 
   */
  private static final long serialVersionUID = 1L;
  
  double lat;
  double lng;
  String latField;
  String lngField;

  int nextOffset = 0;
  
  /**
   * Provide a distance filter based from a center point with a radius
   * in miles.
   * @param startingFilter Filter to start from
   * @param lat
   * @param lng
   * @param miles
   * @param latField
   * @param lngField
   */
  public LatLongDistanceFilter(Filter startingFilter, double lat, double lng, double miles, String latField, String lngField) {
    super(startingFilter, miles);
    this.lat = lat;
    this.lng = lng;
    this.latField = latField;
    this.lngField = lngField;
  }
  
  @Override
  public DocIdSet getDocIdSet(IndexReader reader) throws IOException {

    final double[] latIndex = FieldCache.DEFAULT.getDoubles(reader, latField);
    final double[] lngIndex = FieldCache.DEFAULT.getDoubles(reader, lngField);

    final int docBase = nextDocBase;
    nextDocBase += reader.maxDoc();

    return new FilteredDocIdSet(startingFilter.getDocIdSet(reader)) {
      @Override
      protected boolean match(int doc) {
        double x = latIndex[doc];
        double y = lngIndex[doc];
      
        // round off lat / longs if necessary
        //      x = DistanceHandler.getPrecision(x, precise);
        //      y = DistanceHandler.getPrecision(y, precise);
      
        String ck = Double.toString(x)+","+Double.toString(y);
        Double cachedDistance = distanceLookupCache.get(ck);

        double d;
        if (cachedDistance != null){
          d = cachedDistance.doubleValue();
        } else {
          d = DistanceUtils.getDistanceMi(lat, lng, x, y);
          distanceLookupCache.put(ck, d);
        }

        if (d < distance) {
          // Save distances, so they can be pulled for
          // sorting after filtering is done:
          distances.put(doc+docBase, d);
          return true;
        } else {
          return false;
        }
      }
    };
  }

  /** Returns true if <code>o is equal to this. */
  @Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (!(o instanceof LatLongDistanceFilter)) return false;
    LatLongDistanceFilter other = (LatLongDistanceFilter) o;

    if (!this.startingFilter.equals(other.startingFilter) ||
        this.distance != other.distance ||
        this.lat != other.lat ||
        this.lng != other.lng ||
        !this.latField.equals(other.latField) ||
        !this.lngField.equals(other.lngField)) {
      return false;
    }
    return true;
  }

  /** Returns a hash code value for this object.*/
  @Override
  public int hashCode() {
    int h = Double.valueOf(distance).hashCode();
    h ^= startingFilter.hashCode();
    h ^= Double.valueOf(lat).hashCode();
    h ^= Double.valueOf(lng).hashCode();
    h ^= latField.hashCode();
    h ^= lngField.hashCode();
    return h;
  }
}

Other Lucene examples (source code examples)

Here is a short list of links related to this Lucene LatLongDistanceFilter.java source code file:

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