private void Search()
{
IndexReader indexReader = DirectoryReader.Open(directory);
IndexSearcher indexSearcher = new IndexSearcher(indexReader);
Sort idSort = new Sort(new SortField("id", SortFieldType.INT32));
//--Filter by circle (<= distance from a point)
{
//Search with circle
//note: SpatialArgs can be parsed from a string
SpatialArgs args = new SpatialArgs(SpatialOperation.Intersects,
ctx.MakeCircle(-80.0, 33.0, DistanceUtils.Dist2Degrees(200, DistanceUtils.EARTH_MEAN_RADIUS_KM)));
Filter filter = strategy.MakeFilter(args);
TopDocs docs = indexSearcher.Search(new MatchAllDocsQuery(), filter, 10, idSort);
AssertDocMatchedIds(indexSearcher, docs, 2);
//Now, lets get the distance for the 1st doc via computing from stored point value:
// (this computation is usually not redundant)
Document doc1 = indexSearcher.Doc(docs.ScoreDocs[0].Doc);
String doc1Str = doc1.GetField(strategy.FieldName).GetStringValue();
//assume doc1Str is "x y" as written in newSampleDocument()
int spaceIdx = doc1Str.IndexOf(' ');
double x = double.Parse(doc1Str.Substring(0, spaceIdx - 0), CultureInfo.InvariantCulture);
double y = double.Parse(doc1Str.Substring(spaceIdx + 1), CultureInfo.InvariantCulture);
double doc1DistDEG = ctx.CalcDistance(args.Shape.Center, x, y);
assertEquals(121.6d, DistanceUtils.Degrees2Dist(doc1DistDEG, DistanceUtils.EARTH_MEAN_RADIUS_KM), 0.1);
//or more simply:
assertEquals(121.6d, doc1DistDEG * DistanceUtils.DEG_TO_KM, 0.1);
}
//--Match all, order by distance ascending
{
IPoint pt = ctx.MakePoint(60, -50);
ValueSource valueSource = strategy.MakeDistanceValueSource(pt, DistanceUtils.DEG_TO_KM); //the distance (in km)
Sort distSort = new Sort(valueSource.GetSortField(false)).Rewrite(indexSearcher); //false=asc dist
TopDocs docs = indexSearcher.Search(new MatchAllDocsQuery(), 10, distSort);
AssertDocMatchedIds(indexSearcher, docs, 4, 20, 2);
//To get the distance, we could compute from stored values like earlier.
// However in this example we sorted on it, and the distance will get
// computed redundantly. If the distance is only needed for the top-X
// search results then that's not a big deal. Alternatively, try wrapping
// the ValueSource with CachingDoubleValueSource then retrieve the value
// from the ValueSource now. See LUCENE-4541 for an example.
}
//demo arg parsing
{
SpatialArgs args = new SpatialArgs(SpatialOperation.Intersects,
ctx.MakeCircle(-80.0, 33.0, 1));
SpatialArgs args2 = new SpatialArgsParser().Parse("Intersects(BUFFER(POINT(-80 33),1))", ctx);
assertEquals(args.toString(), args2.toString());
}
indexReader.Dispose();
}
//query builders
public QueryHelper <TModel> SortByDistanceFromPoint(Expression <Func <TModel, object> > exp, double longitude, double latitude, bool desc = false)
{
if (sort == null)
{
sort = new Sort();
sorts = new List <SortField>();
}
string key = getName(exp.Body.ToString());
var strat = new PointVectorStrategy(ctx, key);
IPoint pt = ctx.MakePoint(longitude, longitude);
ValueSource valueSource = strat.MakeDistanceValueSource(pt, DistanceUtils.DEG_TO_KM); //the distance (in km)
sort = new Sort(valueSource.GetSortField(desc)); //.Rewrite(indexSearcher);//false=asc dist
return(this);
}