AreaSimilarity.cs

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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.
 */

using System;
using Lucene.Net.Search;
using Spatial4n.Core.Context;
using Spatial4n.Core.Shapes;

namespace Lucene.Net.Spatial.BBox
{
    public class AreaSimilarity : BBoxSimilarity
    {
       /*
        * Properties associated with the query envelope
        */
        private readonly Rectangle queryExtent;
        private readonly double queryArea;

        private readonly double targetPower;
        private readonly double queryPower;

        public AreaSimilarity(Rectangle queryExtent, double queryPower, double targetPower)
        {
            this.queryExtent = queryExtent;
            this.queryArea = queryExtent.GetArea(null);

            this.queryPower = queryPower;
            this.targetPower = targetPower;

            //  if (this.qryMinX > queryExtent.getMaxX()) {
            //    this.qryCrossedDateline = true;
            //    this.qryArea = Math.abs(qryMaxX + 360.0 - qryMinX) * Math.abs(qryMaxY - qryMinY);
            //  } else {
            //    this.qryArea = Math.abs(qryMaxX - qryMinX) * Math.abs(qryMaxY - qryMinY);
            //  }
        }

        public AreaSimilarity(Rectangle queryExtent)
            : this(queryExtent, 2.0, 0.5)
        {
        }

        public String GetDelimiterQueryParameters()
        {
            return queryExtent + ";" + queryPower + ";" + targetPower;
        }

        public double Score(Rectangle target, Explanation exp)
        {
            if (target == null || queryArea <= 0)
            {
                return 0;
            }
            double targetArea = target.GetArea(null);
            if (targetArea <= 0)
            {
                return 0;
            }
            double score = 0;

            double top = Math.Min(queryExtent.GetMaxY(), target.GetMaxY());
            double bottom = Math.Max(queryExtent.GetMinY(), target.GetMinY());
            double height = top - bottom;
            double width = 0;

            // queries that cross the date line
            if (queryExtent.GetCrossesDateLine())
            {
                // documents that cross the date line
                if (target.GetCrossesDateLine())
                {
                    double left = Math.Max(queryExtent.GetMinX(), target.GetMinX());
                    double right = Math.Min(queryExtent.GetMaxX(), target.GetMaxX());
                    width = right + 360.0 - left;
                }
                else
                {
                    double qryWestLeft = Math.Max(queryExtent.GetMinX(), target.GetMaxX());
                    double qryWestRight = Math.Min(target.GetMaxX(), 180.0);
                    double qryWestWidth = qryWestRight - qryWestLeft;
                    if (qryWestWidth > 0)
                    {
                        width = qryWestWidth;
                    }
                    else
                    {
                        double qryEastLeft = Math.Max(target.GetMaxX(), -180.0);
                        double qryEastRight = Math.Min(queryExtent.GetMaxX(), target.GetMaxX());
                        double qryEastWidth = qryEastRight - qryEastLeft;
                        if (qryEastWidth > 0)
                        {
                            width = qryEastWidth;
                        }
                    }
                }
            }
            else
            { // queries that do not cross the date line

                if (target.GetCrossesDateLine())
                {
                    double tgtWestLeft = Math.Max(queryExtent.GetMinX(), target.GetMinX());
                    double tgtWestRight = Math.Min(queryExtent.GetMaxX(), 180.0);
                    double tgtWestWidth = tgtWestRight - tgtWestLeft;
                    if (tgtWestWidth > 0)
                    {
                        width = tgtWestWidth;
                    }
                    else
                    {
                        double tgtEastLeft = Math.Max(queryExtent.GetMinX(), -180.0);
                        double tgtEastRight = Math.Min(queryExtent.GetMaxX(), target.GetMaxX());
                        double tgtEastWidth = tgtEastRight - tgtEastLeft;
                        if (tgtEastWidth > 0)
                        {
                            width = tgtEastWidth;
                        }
                    }
                }
                else
                {
                    double left = Math.Max(queryExtent.GetMinX(), target.GetMinX());
                    double right = Math.Min(queryExtent.GetMaxX(), target.GetMaxX());
                    width = right - left;
                }
            }


            // calculate the score
            if ((width > 0) && (height > 0))
            {
                double intersectionArea = width * height;
                double queryRatio = intersectionArea / queryArea;
                double targetRatio = intersectionArea / targetArea;
                double queryFactor = Math.Pow(queryRatio, queryPower);
                double targetFactor = Math.Pow(targetRatio, targetPower);
                score = queryFactor * targetFactor * 10000.0;

                if (exp != null)
                {
                    //        StringBuilder sb = new StringBuilder();
                    //        sb.append("\nscore=").append(score);
                    //        sb.append("\n  query=").append();
                    //        sb.append("\n  target=").append(target.toString());
                    //        sb.append("\n  intersectionArea=").append(intersectionArea);
                    //        
                    //        sb.append(" queryArea=").append(queryArea).append(" targetArea=").append(targetArea);
                    //        sb.append("\n  queryRatio=").append(queryRatio).append(" targetRatio=").append(targetRatio);
                    //        sb.append("\n  queryFactor=").append(queryFactor).append(" targetFactor=").append(targetFactor);
                    //        sb.append(" (queryPower=").append(queryPower).append(" targetPower=").append(targetPower).append(")");

                    exp.Value = (float) score;
                    exp.Description = GetType().Name;

                    Explanation e = null;

                    exp.AddDetail(e = new Explanation((float)intersectionArea, "IntersectionArea"));
                    e.AddDetail(new Explanation((float)width, "width; Query: " + queryExtent));
                    e.AddDetail(new Explanation((float)height, "height; Target: " + target));

                    exp.AddDetail(e = new Explanation((float)queryFactor, "Query"));
                    e.AddDetail(new Explanation((float)queryArea, "area"));
                    e.AddDetail(new Explanation((float)queryRatio, "ratio"));
                    e.AddDetail(new Explanation((float)queryPower, "power"));

                    exp.AddDetail(e = new Explanation((float)targetFactor, "Target"));
                    e.AddDetail(new Explanation((float)targetArea, "area"));
                    e.AddDetail(new Explanation((float)targetRatio, "ratio"));
                    e.AddDetail(new Explanation((float)targetPower, "power"));
                }
            }
            else if (exp != null)
            {
                exp.Value = 0;
                exp.Description = "Shape does not intersect";
            }
            return score;
        }

        public override bool Equals(object obj)
        {
            var other = obj as AreaSimilarity;
            if (other == null) return false;
            return GetDelimiterQueryParameters().Equals(other.GetDelimiterQueryParameters());
        }

        public override int GetHashCode()
        {
            return GetDelimiterQueryParameters().GetHashCode();
        } 
    }
}