Lucence Spatial Search 3.0.3

Program.cs

namespace LuceneExample
{
    #region Namespaces

    using System;
    using System.Globalization;

    using Lucene.Net.Analysis.Standard;
    using Lucene.Net.Documents;
    using Lucene.Net.Index;
    using Lucene.Net.Search;
    using Lucene.Net.Spatial.Queries;
    using Lucene.Net.Spatial.Vector;
    using Lucene.Net.Store;

    using Spatial4n.Core.Context;
    using Spatial4n.Core.Distance;
    using Spatial4n.Core.Shapes;

    using Directory = Lucene.Net.Store.Directory;
    using Version = Lucene.Net.Util.Version;

    #endregion

    public class SpatialSearch
    {
        private readonly SpatialContext ctx;

        private readonly Directory directory;

        private readonly PointVectorStrategy strategy;

        public SpatialSearch()
        {
            directory = new RAMDirectory();

            ctx = SpatialContext.GEO;
            
            strategy = new PointVectorStrategy(ctx, "location");
        }

        public void indexDocuments()
        {
            var a = new StandardAnalyzer(Version.LUCENE_30);
            using (var indexWriter = new IndexWriter(directory, a, IndexWriter.MaxFieldLength.UNLIMITED))
            {

                indexWriter.AddDocument(newGeoDocument(1, "London", ctx.MakePoint(51.5286416, -0.1015987)));
                indexWriter.AddDocument(newGeoDocument(2, "Watford", ctx.MakePoint(51.6613588, -0.4055098)));
                indexWriter.AddDocument(newGeoDocument(3, "Birmingham", ctx.MakePoint(52.4774376, -1.8636314)));
                indexWriter.AddDocument(newGeoDocument(4, "Edinburgh", ctx.MakePoint(55.9412034, -3.2053834)));
                indexWriter.AddDocument(newGeoDocument(5, "Leeds", ctx.MakePoint(53.8060026, -1.5357323)));
                indexWriter.AddDocument(newGeoDocument(6, "Norwich", ctx.MakePoint(52.640143, 1.2868495)));
                indexWriter.AddDocument(newGeoDocument(7, "New York", ctx.MakePoint(40.7056307, -73.9780035)));
                indexWriter.AddDocument(newGeoDocument(8, "Dubai", ctx.MakePoint(25.073858, 55.2298445)));

                indexWriter.Commit();
                indexWriter.Optimize();
            }
            
        }

        private Document newGeoDocument(int id, String name, Shape shape)
        {
            var doc = new Document();

            doc.Add(new Field("id", id.ToString(CultureInfo.InvariantCulture), Field.Store.YES, Field.Index.ANALYZED));
            doc.Add(new Field("name", name, Field.Store.YES, Field.Index.ANALYZED));
            foreach (AbstractField field in strategy.CreateIndexableFields(shape))
            {
                doc.Add(field);
            }

            doc.Add(new Field(strategy.GetFieldName(), ctx.ToString(shape), Field.Store.YES, Field.Index.NOT_ANALYZED));

            return doc;
        }

        public void search(Double lat, Double lng, int distance)
        {
            var indexReader = IndexReader.Open(directory, true);
            var searcher = new IndexSearcher(indexReader);

            Point p = ctx.MakePoint(lat, lng);
            var args = new SpatialArgs(SpatialOperation.Intersects, ctx.MakeCircle(lat, lng, DistanceUtils.Dist2Degrees(distance, DistanceUtils.EARTH_MEAN_RADIUS_KM)));
            Filter filter = strategy.MakeFilter(args);
            
            //ValueSource valueSource = strategy.MakeDistanceValueSource(p);
            var field = new SortField("score", SortField.SCORE, true);
            var sort = new Sort(field);
            const int limit = 10;
            Query q = strategy.MakeQueryDistanceScore(args);
            TopDocs topDocs = searcher.Search(q, filter, limit, sort);
            ScoreDoc[] scoreDocs = topDocs.ScoreDocs;

            foreach (ScoreDoc s in scoreDocs)
            {
                Document doc = searcher.Doc(s.Doc);
                var docPoint = (Point)ctx.ReadShape(doc.Get(strategy.GetFieldName()));
                double docDistDEG = ctx.GetDistCalc().Distance(args.Shape.GetCenter(), docPoint);
                double docDistInKM = DistanceUtils.Degrees2Dist(docDistDEG, DistanceUtils.EARTH_EQUATORIAL_RADIUS_KM);
                Console.WriteLine("{0}\t{1}\t{2} km ({3})", doc.Get("id"), doc.Get("name"), docDistInKM, s.Score);
            }
        }

        public static void Main()
        {
            var s = new SpatialSearch();

            //Indexes sample documents
            s.indexDocuments();

            //Get Places Within 200 kilometers from 20 Aldermanbury Square.
            s.search(51.516941, -0.0923343, 200);
            Console.ReadLine();
        }
    }

}

Thanks for your code, very helpful. I realized that ctx.MakeCircle(lat, lng) shoud be ctx.MakeCircle(lng,lat). Thanks!