content: package org.apache.solr.search.function.distance;
  /**
   * 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.
   */
  
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.search.Searcher;
  import org.apache.lucene.spatial.DistanceUtils;
  import org.apache.solr.common.SolrException;
  import org.apache.solr.search.function.DocValues;
  import org.apache.solr.search.function.MultiValueSource;
  import org.apache.solr.search.function.ValueSource;
  
  import java.io.IOException;
  import java.util.Map;
  
  
  /**
   * Calculate the p-norm for a Vector.  See http://en.wikipedia.org/wiki/Lp_space
   * <p/>
   * Common cases:
   * <ul>
   * <li>0 = Sparseness calculation</li>
   * <li>1 = Manhattan distance</li>
   * <li>2 = Euclidean distance</li>
   * <li>Integer.MAX_VALUE = infinite norm</li>
   * </ul>
   *
   * @see SquaredEuclideanFunction for the special case
   */
  public class VectorDistanceFunction extends ValueSource {
    protected MultiValueSource source1, source2;
    protected float power;
    protected float oneOverPower;
  
    public VectorDistanceFunction(float power, MultiValueSource source1, MultiValueSource source2) {
      if ((source1.dimension() != source2.dimension())) {
        throw new SolrException(SolrException.ErrorCode.BAD_REQUEST, "Illegal number of sources");
      }
      this.power = power;
      this.oneOverPower = 1 / power;
      this.source1 = source1;
      this.source2 = source2;
    }
  
    protected String name() {
      return "dist";
    }
  
    /**
     * Calculate the distance
     *
     * @param doc The current doc
     * @param dv1 The values from the first MultiValueSource
     * @param dv2 The values from the second MultiValueSource
     * @return The distance
     */
    protected double distance(int doc, DocValues dv1, DocValues dv2) {
      //Handle some special cases:
      double[] vals1 = new double[source1.dimension()];
      double[] vals2 = new double[source1.dimension()];
      dv1.doubleVal(doc, vals1);
      dv2.doubleVal(doc, vals2);
      return DistanceUtils.vectorDistance(vals1, vals2, power, oneOverPower);
    }
  
    @Override
    public DocValues getValues(Map context, IndexReader reader) throws IOException {
  
      final DocValues vals1 = source1.getValues(context, reader);
  
      final DocValues vals2 = source2.getValues(context, reader);
  
  
      return new DocValues() {
        @Override
        public byte byteVal(int doc) {
          return (byte) doubleVal(doc);
        }
  
        @Override
        public short shortVal(int doc) {
          return (short) doubleVal(doc);
        }
  
        @Override
        public float floatVal(int doc) {
          return (float) doubleVal(doc);
        }
  
        @Override
        public int intVal(int doc) {
          return (int) doubleVal(doc);
        }
  
        @Override
        public long longVal(int doc) {
          return (long) doubleVal(doc);
        }
  
        @Override
        public double doubleVal(int doc) {
          return distance(doc, vals1, vals2);
        }
  
        @Override
        public String strVal(int doc) {
          return Double.toString(doubleVal(doc));
        }
  
        @Override
        public String toString(int doc) {
          StringBuilder sb = new StringBuilder();
          sb.append(name()).append('(').append(power).append(',');
          boolean firstTime = true;
          sb.append(vals1.toString(doc)).append(',');
          sb.append(vals2.toString(doc));
          sb.append(')');
          return sb.toString();
        }
      };
    }
  
    @Override
    public void createWeight(Map context, Searcher searcher) throws IOException {
      source1.createWeight(context, searcher);
      source2.createWeight(context, searcher);
    }
  
    @Override
    public boolean equals(Object o) {
      if (this == o) return true;
      if (!(o instanceof VectorDistanceFunction)) return false;
  
      VectorDistanceFunction that = (VectorDistanceFunction) o;
  
      if (Float.compare(that.power, power) != 0) return false;
      if (!source1.equals(that.source1)) return false;
      if (!source2.equals(that.source2)) return false;
  
      return true;
    }
  
    @Override
    public int hashCode() {
      int result = source1.hashCode();
      result = 31 * result + source2.hashCode();
      result = 31 * result + Float.floatToRawIntBits(power);
      return result;
    }
  
    @Override
    public String description() {
      StringBuilder sb = new StringBuilder();
      sb.append(name()).append('(').append(power).append(',');
      sb.append(source1).append(',');
      sb.append(source2);
      sb.append(')');
      return sb.toString();
    }
  
  }
  