/* * FuLiD.java * * Copyright (c) 2002-2015 Alexei Drummond, Andrew Rambaut and Marc Suchard * * This file is part of BEAST. * See the NOTICE file distributed with this work for additional * information regarding copyright ownership and licensing. * * BEAST is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * BEAST is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with BEAST; if not, write to the * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, * Boston, MA 02110-1301 USA */ package dr.app.treestat.statistics; import dr.evolution.tree.NodeRef; import dr.evolution.tree.Tree; /** * @author Alexei Drummond * * @version $Id: FuLiD.java,v 1.2 2005/09/28 13:50:56 rambaut Exp $ */ public class FuLiD extends AbstractTreeSummaryStatistic { private FuLiD() { } public double[] getSummaryStatistic(Tree tree) { double externalLength = 0.0; double internalLength = 0.0; int externalNodeCount = tree.getExternalNodeCount(); for (int i = 0; i < externalNodeCount; i++) { NodeRef node = tree.getExternalNode(i); NodeRef parent = tree.getParent(node); externalLength += tree.getNodeHeight(parent) - tree.getNodeHeight(node); } int internalNodeCount = tree.getInternalNodeCount(); for (int i = 0; i < internalNodeCount; i++) { NodeRef node = tree.getInternalNode(i); if (!tree.isRoot(node)) { NodeRef parent = tree.getParent(node); internalLength += tree.getNodeHeight(parent) - tree.getNodeHeight(node); } } int n = externalNodeCount; double total = externalLength + internalLength; // difference in expectations double D = total - a(n)*externalLength; // normalized D /= Math.sqrt(u(n)*total + (v(n)*(total*total))); return new double[] { D }; } private double a(int n) { double a = 0.0; for (int k = 1; k < n; k++) { a += 1/(double)k; } return a; } private double b(int n) { double b = 0.0; for (int k = 1; k < n; k++) { b += 1/(double)(k*k); } return b; } private double c(int n) { if (n==2) return 1.0; double an = a(n); double c = 2.0 * (n * an - 2.0 * (n - 1.0)); c /= (n-1)*(n-2); return c; } private double v(int n) { double an2 = a(n); an2 *= an2; double v = 1 + (an2/(b(n)+an2)) * (c(n)-((n+1)/(n-1))); return v; } private double u(int n) { return a(n) - 1 - v(n); } public String getSummaryStatisticName() { return FACTORY.getSummaryStatisticName(); } public String getSummaryStatisticDescription() { return FACTORY.getSummaryStatisticDescription(); } public String getSummaryStatisticReference() { return FACTORY.getSummaryStatisticReference(); } public boolean allowsPolytomies() { return FACTORY.allowsPolytomies(); } public boolean allowsNonultrametricTrees() { return FACTORY.allowsNonultrametricTrees(); } public boolean allowsUnrootedTrees() { return FACTORY.allowsUnrootedTrees(); } public SummaryStatisticDescription.Category getCategory() { return FACTORY.getCategory(); } public static final TreeSummaryStatistic.Factory FACTORY = new TreeSummaryStatistic.Factory() { public TreeSummaryStatistic createStatistic() { return new FuLiD(); } public String getSummaryStatisticName() { return "Fu & Li's D"; } public String getSummaryStatisticDescription() { return "The normalized difference between total tree length and external branch tree length. " + "Note that this implementation uses branch lengths rather than the counts of mutations (this " + "has a nice side-effect of taking into account complex mutation models.)"; } public String getSummaryStatisticReference() { return "Fu & Li (1993)"; } public boolean allowsPolytomies() { return false; } public boolean allowsNonultrametricTrees() { return false; } public boolean allowsUnrootedTrees() { return false; } public SummaryStatisticDescription.Category getCategory() { return SummaryStatisticDescription.Category.POPULATION_GENETIC; } }; }