ext/OGDF/src/energybased/multilevelmixer/RandomMerger.cpp

   1 /*
   2  * $Revision: 2523 $
   3  *
   4  * last checkin:
   5  *   $Author: gutwenger $
   6  *   $Date: 2012-07-02 20:59:27 +0200 (Mon, 02 Jul 2012) $
   7  ***************************************************************/
   8
   9 /** \file
  10  * \brief Merges nodes with neighbour to get a Multilevel Graph
  11  *
  12  * \author Gereon Bartel
  13  *
  14  * \par License:
  15  * This file is part of the Open Graph Drawing Framework (OGDF).
  16  *
  17  * \par
  18  * Copyright (C)<br>
  19  * See README.txt in the root directory of the OGDF installation for details.
  20  *
  21  * \par
  22  * This program is free software; you can redistribute it and/or
  23  * modify it under the terms of the GNU General Public License
  24  * Version 2 or 3 as published by the Free Software Foundation;
  25  * see the file LICENSE.txt included in the packaging of this file
  26  * for details.
  27  *
  28  * \par
  29  * This program is distributed in the hope that it will be useful,
  30  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  31  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  32  * GNU General Public License for more details.
  33  *
  34  * \par
  35  * You should have received a copy of the GNU General Public
  36  * License along with this program; if not, write to the Free
  37  * Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  38  * Boston, MA 02110-1301, USA.
  39  *
  40  * \see  http://www.gnu.org/copyleft/gpl.html
  41  ***************************************************************/
  42
  43 #include <ogdf/energybased/multilevelmixer/RandomMerger.h>
  44
  45 namespace ogdf {
  46
  47 RandomMerger::RandomMerger()
  48 :m_levelSizeFactor(2.0)
  49 {
  50 }
  51
  52 bool RandomMerger::buildOneLevel(MultilevelGraph &MLG)
  53 {
  54         Graph &G = MLG.getGraph();
  55         int level = MLG.getLevel() + 1;
  56         int numNodes = G.numberOfNodes();
  57
  58         if (numNodes <= 3) {
  59                 return false;
  60         }
  61
  62         node v;
  63         int index = 0;
  64         Array<node> candidates(numNodes);
  65         forall_nodes(v, G) {
  66                 candidates[index] = v;
  67                 index++;
  68         }
  69
  70         int candSize = candidates.size();
  71         while (candSize > numNodes / m_levelSizeFactor)
  72         {
  73                 index = randomNumber(0, candSize-1);
  74                 node mergeNode = candidates[index];
  75                 candidates[index] = candidates[candSize-1];
  76                 candSize--;
  77                 node parent;
  78
  79                 if (mergeNode->degree() > 0) {
  80                         int index = randomNumber(0, mergeNode->degree()-1);
  81                         int i = 0;
  82                         adjEntry adj;
  83                         forall_adj(adj, mergeNode) {
  84                                 if (i == index) {
  85                                         parent = adj->twinNode();
  86                                         break;
  87                                 } else {
  88                                         i++;
  89                                 }
  90                         }
  91                 } else {
  92                         do {
  93                                 index = randomNumber(0, candSize-1);
  94                                 parent = candidates[index];
  95                         } while (parent == mergeNode);
  96                         candidates[index] = candidates[candSize-1];
  97                         candSize--;
  98                 }
  99
 100                 NodeMerge * NM = new NodeMerge(level);
 101                 bool ret = MLG.changeNode(NM, parent, MLG.radius(parent), mergeNode);
 102                 OGDF_ASSERT( ret );
 103                 MLG.moveEdgesToParent(NM, mergeNode, parent, true, m_adjustEdgeLengths);
 104                 ret = MLG.postMerge(NM, mergeNode);
 105                 if( !ret ) {
 106                         delete NM;
 107                 }
 108         }
 109
 110         return true;
 111 }
 112
 113
 114 void RandomMerger::setFactor(double factor)
 115 {
 116         m_levelSizeFactor = factor;
 117 }
 118
 119 } // namespace ogdf