Java tutorial
/* * 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.flink.graph.library.clustering.undirected; import org.apache.commons.lang3.builder.EqualsBuilder; import org.apache.commons.lang3.builder.HashCodeBuilder; import org.apache.flink.api.java.DataSet; import org.apache.flink.graph.AbstractGraphAnalytic; import org.apache.flink.graph.Graph; import org.apache.flink.graph.asm.dataset.Count; import org.apache.flink.graph.asm.result.PrintableResult; import org.apache.flink.graph.library.clustering.undirected.TriadicCensus.Result; import org.apache.flink.graph.library.metric.undirected.VertexMetrics; import org.apache.flink.types.CopyableValue; import org.apache.flink.util.Preconditions; import java.math.BigInteger; import java.text.NumberFormat; import static org.apache.flink.api.common.ExecutionConfig.PARALLELISM_DEFAULT; /** * A triad is formed by three connected or unconnected vertices in a graph. * The triadic census counts the occurrences of each type of triad. * <p> * The four types of undirected triads are formed with 0, 1, 2, or 3 * connecting edges. * <p> * http://vlado.fmf.uni-lj.si/pub/networks/doc/triads/triads.pdf * * @param <K> graph ID type * @param <VV> vertex value type * @param <EV> edge value type */ public class TriadicCensus<K extends Comparable<K> & CopyableValue<K>, VV, EV> extends AbstractGraphAnalytic<K, VV, EV, Result> { private Count<TriangleListing.Result<K>> triangleCount; private VertexMetrics<K, VV, EV> vertexMetrics; // Optional configuration private int littleParallelism = PARALLELISM_DEFAULT; /** * Override the parallelism of operators processing small amounts of data. * * @param littleParallelism operator parallelism * @return this */ public TriadicCensus<K, VV, EV> setLittleParallelism(int littleParallelism) { this.littleParallelism = littleParallelism; return this; } @Override public TriadicCensus<K, VV, EV> run(Graph<K, VV, EV> input) throws Exception { super.run(input); triangleCount = new Count<>(); DataSet<TriangleListing.Result<K>> triangles = input.run(new TriangleListing<K, VV, EV>() .setSortTriangleVertices(false).setLittleParallelism(littleParallelism)); triangleCount.run(triangles); vertexMetrics = new VertexMetrics<K, VV, EV>().setParallelism(littleParallelism); input.run(vertexMetrics); return this; } @Override public Result getResult() { // vertex metrics BigInteger bigVertexCount = BigInteger.valueOf(vertexMetrics.getResult().getNumberOfVertices()); BigInteger bigEdgeCount = BigInteger.valueOf(vertexMetrics.getResult().getNumberOfEdges()); BigInteger bigTripletCount = BigInteger.valueOf(vertexMetrics.getResult().getNumberOfTriplets()); // triangle count BigInteger bigTriangleCount = BigInteger.valueOf(triangleCount.getResult()); BigInteger one = BigInteger.ONE; BigInteger two = BigInteger.valueOf(2); BigInteger three = BigInteger.valueOf(3); BigInteger six = BigInteger.valueOf(6); // counts as ordered in TriadicCensus.Result BigInteger[] counts = new BigInteger[4]; // triads with three connecting edges = closed triplet = triangle counts[3] = bigTriangleCount; // triads with two connecting edges = open triplet; // deduct each triplet having been counted three times per triangle counts[2] = bigTripletCount.subtract(bigTriangleCount.multiply(three)); // triads with one connecting edge; each edge pairs with `vertex count - 2` vertices // then deduct twice for each open triplet and three times for each triangle counts[1] = bigEdgeCount.multiply(bigVertexCount.subtract(two)).subtract(counts[2].multiply(two)) .subtract(counts[3].multiply(three)); // triads with zero connecting edges; // (vertex count choose 3) minus earlier counts counts[0] = bigVertexCount.multiply(bigVertexCount.subtract(one)).multiply(bigVertexCount.subtract(two)) .divide(six).subtract(counts[1]).subtract(counts[2]).subtract(counts[3]); return new Result(counts); } /** * Wraps triadic census metrics. */ public static class Result implements PrintableResult { private final BigInteger[] counts; public Result(BigInteger... counts) { Preconditions.checkArgument(counts.length == 4, "Expected 4 counts but received " + counts.length); this.counts = counts; } public Result(long... counts) { Preconditions.checkArgument(counts.length == 4, "Expected 4 counts but received " + counts.length); this.counts = new BigInteger[counts.length]; for (int i = 0; i < counts.length; i++) { this.counts[i] = BigInteger.valueOf(counts[i]); } } /** * Get the count of "03" triads which have zero connecting vertices. * * @return count of "03" triads */ public BigInteger getCount03() { return counts[0]; } /** * Get the count of "12" triads which have one edge among the vertices. * * @return count of "12" triads */ public BigInteger getCount12() { return counts[1]; } /** * Get the count of "21" triads which have two edges among the vertices * and form a open triplet. * * @return count of "21" triads */ public BigInteger getCount21() { return counts[2]; } /** * Get the count of "30" triads which have three edges among the vertices * and form a closed triplet, a triangle. * * @return count of "30" triads */ public BigInteger getCount30() { return counts[3]; } /** * Get the array of counts. * * The order of the counts is from least to most connected: * 03, 12, 21, 30 * * @return array of counts */ public BigInteger[] getCounts() { return counts; } @Override public String toPrintableString() { NumberFormat nf = NumberFormat.getInstance(); return "03: " + nf.format(getCount03()) + "; 12: " + nf.format(getCount12()) + "; 21: " + nf.format(getCount21()) + "; 30: " + nf.format(getCount30()); } @Override public int hashCode() { return new HashCodeBuilder().append(counts).hashCode(); } @Override public boolean equals(Object obj) { if (obj == null) { return false; } if (obj == this) { return true; } if (obj.getClass() != getClass()) { return false; } Result rhs = (Result) obj; return new EqualsBuilder().append(counts, rhs.counts).isEquals(); } } }