001/* 002 * Copyright 2006 - 2013 003 * Stefan Balev <stefan.balev@graphstream-project.org> 004 * Julien Baudry <julien.baudry@graphstream-project.org> 005 * Antoine Dutot <antoine.dutot@graphstream-project.org> 006 * Yoann Pigné <yoann.pigne@graphstream-project.org> 007 * Guilhelm Savin <guilhelm.savin@graphstream-project.org> 008 * 009 * This file is part of GraphStream <http://graphstream-project.org>. 010 * 011 * GraphStream is a library whose purpose is to handle static or dynamic 012 * graph, create them from scratch, file or any source and display them. 013 * 014 * This program is free software distributed under the terms of two licenses, the 015 * CeCILL-C license that fits European law, and the GNU Lesser General Public 016 * License. You can use, modify and/ or redistribute the software under the terms 017 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following 018 * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by 019 * the Free Software Foundation, either version 3 of the License, or (at your 020 * option) any later version. 021 * 022 * This program is distributed in the hope that it will be useful, but WITHOUT ANY 023 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A 024 * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. 025 * 026 * You should have received a copy of the GNU Lesser General Public License 027 * along with this program. If not, see <http://www.gnu.org/licenses/>. 028 * 029 * The fact that you are presently reading this means that you have had 030 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms. 031 */ 032package org.graphstream.algorithm.randomWalk; 033 034import org.graphstream.graph.Edge; 035import org.graphstream.graph.Node; 036 037/** 038 * A base entity for the {@link RandomWalk} algorithm. 039 */ 040public abstract class Entity { 041 042 /** 043 * The shared information. 044 */ 045 protected RandomWalk.Context context; 046 047 /** 048 * The current node the entity is on. 049 */ 050 protected Node current; 051 052 /** 053 * Should initialize the entity, starting it on the given node. 054 * @param start The node on which the entity starts. 055 */ 056 void init(RandomWalk.Context context, Node start) { 057 this.current = start; 058 this.context = context; 059 } 060 061 /** 062 * Should move the entity from its current node to another. 063 */ 064 abstract void step(); 065 066 /** 067 * The weight of an edge. 068 * @param e The edge. 069 * @return The weight of the edge. 070 */ 071 protected double weight(Edge e) { 072 if (!e.hasAttribute(context.weightAttribute)) 073 return 1.0; 074 075 return e.getNumber(context.weightAttribute); 076 } 077}