// reference: http://en.wikipedia.org/wiki/Hilbert_curve
//convert (x,y) to d
public static long XYtoD(long n, LongPoint point)
{
long rx, ry, s, d = 0;
for (s = n / 2; s > 0; s /= 2)
{
rx = (point.x & s) > 0 ? 1 : 0;
ry = (point.y & s) > 0 ? 1 : 0;
d += s * s * ((3 * rx) ^ ry);
Rot(s, point, rx, ry);
}
return(d);
}
public void LongPointTest()
{
var analyzer = new WhitespaceAnalyzer();
var iwc = new IndexWriterConfig(analyzer);
iwc.SetOpenMode(IndexWriterConfigOpenMode.CREATE);
//インデックス作成---------------------------------------------
DateTime baseDate = DateTime.Parse("2020/07/16 08:00:00");
var ram = new RAMDirectory();
var writer = new IndexWriter(ram, iwc);
try {
for (int i = 0; i < 10; i++)
{
var doc = new Document();
doc.Add(new TextField("text", "hoge foo", FieldStore.YES));
DateTime tmp = baseDate.AddDays(i);
long l = long.Parse(tmp.ToString("yyyyMMddHHmmss"));
doc.Add(new LongPoint("date", l));
doc.Add(new StoredField("date", l));
writer.AddDocument(doc);
}
} finally {
writer.Close();
}
//検索------------------------------------------------------------
TermQuery tq = new TermQuery(new Term("text", "foo"));
Query rq = LongPoint.NewRangeQuery("date", 20200717000000, 20200719000000);
BooleanQueryBuilder b = new BooleanQueryBuilder();
b.Add(tq, BooleanClauseOccur.MUST); //AND条件
b.Add(rq, BooleanClauseOccur.FILTER); //AND条件（スコアリングに関与しない）
Query q = b.Build();
DirectoryReader dr = DirectoryReader.Open(ram);
IndexSearcher searcher = new IndexSearcher(dr);
ScoreDoc[] hits = searcher.Search(q, 100).ScoreDocs;
for (int i = 0; i < hits.Length; i++)
{
var doc = searcher.Doc(hits[i].Doc);
Debug.WriteLine(DateTime.ParseExact(doc.Get("date"), "yyyyMMddHHmmss", null));
}
Assert.AreEqual(hits.Length, 2);
}
//rotate/flip a quadrant appropriately
private static void Rot(long n, LongPoint point, long rx, long ry)
{
if (ry == 0)
{
if (rx == 1)
{
point.x = n - 1 - point.x;
point.y = n - 1 - point.y;
}
//Swap x and y
long t = point.x;
point.x = point.y;
point.y = t;
}
}
//convert d to (x,y)
public static LongPoint DtoXY(long n, long d)
{
long rx, ry, s, t = d;
var point = new LongPoint(0, 0);
for (s = 1; s <= n; s *= 2)
{
rx = 1 & (t / 2);
ry = 1 & (t ^ rx);
Rot(s, point, rx, ry);
point.x += s * rx;
point.y += s * ry;
t /= 4;
}
return(point);
}
