iverase commented on code in PR #1017: URL: https://github.com/apache/lucene/pull/1017#discussion_r927333254
########## lucene/core/src/java/org/apache/lucene/document/ShapeDocValuesField.java: ########## @@ -0,0 +1,896 @@ +/* + * 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. + */ +package org.apache.lucene.document; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Comparator; +import java.util.List; +import org.apache.lucene.analysis.Analyzer; +import org.apache.lucene.analysis.TokenStream; +import org.apache.lucene.document.ShapeField.DecodedTriangle.TYPE; +import org.apache.lucene.document.ShapeField.QueryRelation; +import org.apache.lucene.document.SpatialQuery.EncodedRectangle; +import org.apache.lucene.index.DocValuesType; +import org.apache.lucene.index.IndexableFieldType; +import org.apache.lucene.index.PointValues.Relation; +import org.apache.lucene.search.Query; +import org.apache.lucene.store.ByteArrayDataInput; +import org.apache.lucene.store.ByteBuffersDataOutput; +import org.apache.lucene.store.DataInput; +import org.apache.lucene.util.ArrayUtil; +import org.apache.lucene.util.BytesRef; + +/** A doc values field representation for {@link LatLonShape} and {@link XYShape} */ +public final class ShapeDocValuesField extends Field { + private final ShapeComparator shapeComparator; + + private static final FieldType FIELD_TYPE = new FieldType(); + + static { + FIELD_TYPE.setDocValuesType(DocValuesType.BINARY); + FIELD_TYPE.setOmitNorms(true); + FIELD_TYPE.freeze(); + } + + /** + * Creates a {@ShapeDocValueField} instance from a shape tessellation + * + * @param name The Field Name (must not be null) + * @param tessellation The tessellation (must not be null) + */ + ShapeDocValuesField(String name, List<ShapeField.DecodedTriangle> tessellation) { + super(name, FIELD_TYPE); + BytesRef b = computeBinaryValue(tessellation); + this.fieldsData = b; + try { + this.shapeComparator = new ShapeComparator(b); + } catch (IOException e) { + throw new IllegalArgumentException("unable to read binary shape doc value field. ", e); + } + } + + /** Creates a {@code ShapeDocValue} field from a given serialized value */ + ShapeDocValuesField(String name, BytesRef binaryValue) { + super(name, FIELD_TYPE); + this.fieldsData = binaryValue; + try { + this.shapeComparator = new ShapeComparator(binaryValue); + } catch (IOException e) { + throw new IllegalArgumentException("unable to read binary shape doc value field. ", e); + } + } + + /** The name of the field */ + @Override + public String name() { + return name; + } + + /** Gets the {@code IndexableFieldType} for this ShapeDocValue field */ + @Override + public IndexableFieldType fieldType() { + return FIELD_TYPE; + } + + /** Currently there is no string representation for the ShapeDocValueField */ + @Override + public String stringValue() { + return null; + } + + /** TokenStreams are not yet supported */ + @Override + public TokenStream tokenStream(Analyzer analyzer, TokenStream reuse) { + return null; + } + + /** create a shape docvalue field from indexable fields */ + public static ShapeDocValuesField createDocValueField(String fieldName, Field[] indexableFields) { + ArrayList<ShapeField.DecodedTriangle> tess = new ArrayList<>(indexableFields.length); + final byte[] scratch = new byte[7 * Integer.BYTES]; + for (Field f : indexableFields) { + BytesRef br = f.binaryValue(); + assert br.length == 7 * ShapeField.BYTES; + System.arraycopy(br.bytes, br.offset, scratch, 0, 7 * ShapeField.BYTES); + ShapeField.DecodedTriangle t = new ShapeField.DecodedTriangle(); + ShapeField.decodeTriangle(scratch, t); + tess.add(t); + } + return new ShapeDocValuesField(fieldName, tess); + } + + /** Returns the number of terms (tessellated triangles) for this shape */ + public int numberOfTerms() { + return shapeComparator.numberOfTerms(); + } + + /** Creates a geometry query for shape docvalues */ + public static Query newGeometryQuery( + final String field, final QueryRelation relation, Object... geometries) { + return null; + // TODO + // return new ShapeDocValuesQuery(field, relation, geometries); + } + + /** Compute the spatial relation of this shape and a bounding box (in encoded space) */ + public Relation relate(final int minX, final int maxX, final int minY, final int maxY) + throws IOException { + return shapeComparator.relate(minX, maxX, minY, maxY); + } + + /** returns the min x value for the shape's bounding box */ + public int getMinX() { + return shapeComparator.getMinX(); + } + + /** returns the min y value for the shape's bounding box */ + public int getMinY() { + return shapeComparator.getMinY(); + } + + /** returns the max x value for the shape's bounding box */ + public int getMaxX() { + return shapeComparator.getMaxX(); + } + + /** returns the max y value for the shape's bounding box */ + public int getMaxY() { + return shapeComparator.getMaxY(); + } + + /** Retrieves the x centroid location for the geometry(s) */ + public int getCentroidX() { + return shapeComparator.getCentroidX(); + } + + /** Retrieves the y centroid location for the geometry(s) */ + public int getCentroidY() { + return shapeComparator.getCentroidY(); + } + + /** + * Retrieves the highest dimensional type (POINT, LINE, TRIANGLE) for computing the geometry(s) + * centroid + */ + public TYPE getHighestDimensionType() { + return shapeComparator.getHighestDimension(); + } + + private BytesRef computeBinaryValue(List<ShapeField.DecodedTriangle> tessellation) { + try { + // dfs order serialization + List<TreeNode> dfsSerialized = new ArrayList<>(tessellation.size()); + buildTree(tessellation, dfsSerialized); + Writer w = new Writer(dfsSerialized); + return w.getBytesRef(); + } catch (IOException e) { + throw new RuntimeException("Internal error building LatLonShapeDocValues. Got ", e); + } + } + + /** main entry point to build the tessellation tree * */ + public TreeNode buildTree( + List<ShapeField.DecodedTriangle> tessellation, List<TreeNode> dfsSerialized) + throws IOException { + if (tessellation.size() == 1) { + ShapeField.DecodedTriangle t = tessellation.get(0); + TreeNode node = new TreeNode(t); + if (t.type == TYPE.LINE) { + node.midX /= node.length; + node.midY /= node.length; + } else if (t.type == TYPE.TRIANGLE) { + node.midX /= node.signedArea; + node.midY /= node.signedArea; + } + node.highestType = t.type; + dfsSerialized.add(node); + return node; + } + TreeNode[] triangles = new TreeNode[tessellation.size()]; + int i = 0; + int minY = Integer.MAX_VALUE; + int minX = Integer.MAX_VALUE; + int maxY = Integer.MIN_VALUE; + int maxX = Integer.MIN_VALUE; + + // running stats for computing centroid + double totalSignedArea = 0; + double totalLength = 0; + double numXPnt = 0; + double numYPnt = 0; + double numXLin = 0; + double numYLin = 0; + double numXPly = 0; + double numYPly = 0; + TYPE highestType = TYPE.POINT; + + for (ShapeField.DecodedTriangle t : tessellation) { + TreeNode node = new TreeNode(t); + triangles[i++] = node; + // compute the bbox values up front + minY = Math.min(minY, node.minY); + minX = Math.min(minX, node.minX); + maxY = Math.max(maxY, node.maxY); + maxX = Math.max(maxX, node.maxX); + + // compute the running centroid stats + totalSignedArea += node.signedArea; // non-zero if any components are triangles + totalLength += node.length; // non-zero if any components are line segments + if (t.type == TYPE.POINT) { + numXPnt += node.midX; + numYPnt += node.midY; + } else if (t.type == TYPE.LINE) { + if (highestType == TYPE.POINT) { + highestType = TYPE.LINE; + } + numXLin += node.midX; + numYLin += node.midY; + } else { + if (highestType != TYPE.TRIANGLE) { + highestType = TYPE.TRIANGLE; + } + numXPly += node.midX; + numYPly += node.midY; + } + } + TreeNode root = createTree(triangles, 0, triangles.length - 1, false, null, dfsSerialized); + + // pull up min values for the root node so the bbox is consistent + root.minY = minY; + root.minX = minX; + + // set the highest dimensional type + root.highestType = highestType; + + // compute centroid values for the root node so the centroid is consistent Review Comment: Thanks @nknize for the references. I have no time to look in detail into the algorithms so to keep me sane I just try to compute the centroid using an ubiquitous library JTS (which as well [refers](https://github.com/locationtech/jts/blob/master/modules/core/src/main/java/org/locationtech/jts/algorithm/Centroid.java) to the documentation you pointed above) to compute the centroid of the polygon I gave as example: ``` String mp = "MULTIPOLYGON(((-80 -10, -40 -10, -40 10, -80 10, -80 -10)),((10 -1, 11 -1, 11 1, 10 1, 10 -1)))"; WKTReader wktReader = new WKTReader(); Coordinate c = Centroid.getCentroid(wktReader.read(mp)); String wkt = "POINT(" + c.getX() + " " + c.getY() + ")"; ``` And the result is: ``` POINT(-59.82418952618454 -0.0) ``` Which is where I was expecting the centroid to be located: <img width="1014" alt="image" src="https://user-images.githubusercontent.com/29038686/180377042-6ff46b36-0fae-434d-8742-82088e943320.png";> Then I wrote a test using your implementation: ``` public void testLatLonMultiPolygonCentroid() throws Exception { String mp = "MULTIPOLYGON(((-80 -10, -40 -10, -40 10, -80 10, -80 -10)),((10 -1, 11 -1, 11 1, 10 1, 10 -1)))"; Polygon[] p = (Polygon[]) SimpleWKTShapeParser.parse(mp); List<ShapeField.DecodedTriangle> tess = getTessellation(p[0]); tess.addAll(getTessellation(p[1])); ShapeDocValuesField dvField = LatLonShape.createDocValueField(FIELD_NAME, tess); assertEquals(0d, GeoEncodingUtils.decodeLatitude(dvField.getCentroidY()), 1E-8); // POINT(-59.82418952618454 0.0) assertEquals(-59.82418952618454 , GeoEncodingUtils.decodeLongitude(dvField.getCentroidX()), 1E-8); assertEquals(ShapeField.DecodedTriangle.TYPE.TRIANGLE, dvField.getHighestDimensionType()); } ``` And the test fails: ``` Expected :-59.82418952618454 Actual :4.51269194483757 ``` So the centroid is way off the expected position, could you check if I am doing something wrong? <img width="966" alt="image" src="https://user-images.githubusercontent.com/29038686/180377577-3e589aed-dfa2-4172-8a97-aa9acc5eb4ee.png";> -- This is an automated message from the Apache Git Service. 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