MinimumSpanningTree.cpp

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/*  Copyright (C) 2008 National Institute For Space Research (INPE) - Brazil.

    This file is part of the TerraLib - a Framework for building GIS enabled applications.

    TerraLib 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 3 of the License,
    or (at your option) any later version.

    TerraLib 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 TerraLib. See COPYING. If not, write to
    TerraLib Team at <terralib-team@terralib.org>.
 */

/*!
  \file terralib/sa/core/MinimumSpanningTree.cpp

  \brief This file contains a class that represents the Minimum Spanning Tree operation.

  \reference Boost BGL.
*/

//TerraLib
#include "../../datatype/SimpleData.h"
#include "../../graph/core/AbstractGraph.h"
#include "../../graph/core/AbstractGraphFactory.h"
#include "../../graph/core/Edge.h"
#include "../../graph/core/GraphMetadata.h"
#include "../../graph/core/Vertex.h"
#include "../../graph/iterator/MemoryIterator.h"
#include "../../graph/Globals.h"
#include "MinimumSpanningTree.h"
#include "Utils.h"

//STL
#include <cassert>

//Boost
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/kruskal_min_spanning_tree.hpp>

te::sa::MinimumSpanningTree::MinimumSpanningTree(te::graph::AbstractGraph* inputGraph) : m_inputGraph(inputGraph)
{
}

te::sa::MinimumSpanningTree::~MinimumSpanningTree() = default;

te::graph::AbstractGraph* te::sa::MinimumSpanningTree::kruskal(int weightAttrIdx)
{
  //create iterator
  te::graph::MemoryIterator* iterator = new te::graph::MemoryIterator(m_inputGraph);

  std::size_t nEdge = iterator->getEdgeInteratorCount();
  std::size_t nVertex = iterator->getVertexInteratorCount();

  //create boost graph
  typedef boost::adjacency_list < boost::vecS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<boost::edge_weight_t, int > > boostGraph;

  typedef std::pair < int, int > boostEdge;

  std::vector<boostEdge> edge_vec;

  std::vector<double> weight_vec;

  te::graph::Edge* edge = iterator->getFirstEdge();

  while(edge)
  {
    edge_vec.push_back(boostEdge(edge->getIdFrom(), edge->getIdTo()));

    weight_vec.push_back(te::sa::GetDataValue(edge->getAttributes()[weightAttrIdx]));

    edge = iterator->getNextEdge();
  }

  boostGraph graph(nVertex);

  boost::property_map<boostGraph, boost::edge_weight_t>::type weightmap = boost::get(boost::edge_weight, graph);

  for(std::size_t t = 0; t < nEdge; ++t)
  {
    boost::graph_traits<boostGraph>::edge_descriptor e;

    bool inserted;

    boost::tie(e, inserted) = boost::add_edge(edge_vec[t].first, edge_vec[t].second, graph);

    weightmap[e] = (int)weight_vec[t];
  }

  //run kruskal algorithm
  typedef boost::graph_traits<boostGraph>::edge_descriptor Edge;

  boost::property_map<boostGraph, boost::edge_weight_t>::type weight = boost::get(boost::edge_weight, graph);

  std::vector<Edge> spanning_tree;

  kruskal_minimum_spanning_tree(graph, std::back_inserter(spanning_tree));

  //create output graph
  te::graph::AbstractGraph* graphOut = createGraph();

  //create edge weight property
  int edgeWeightIdx = te::sa::AddGraphEdgeAttribute(graphOut, TE_SA_SKATER_ATTR_WEIGHT_NAME, te::dt::DOUBLE_TYPE);
  int size = graphOut->getMetadata()->getEdgePropertySize();

  //copy the minimum spanning tree graph 
  for(std::size_t t = 0; t < spanning_tree.size(); ++t)
  {
    Edge eCur = spanning_tree[t];

    int vertexSourceId = static_cast<int>(boost::source(eCur, graph));
    int vertexTargetId = static_cast<int>(boost::target(eCur, graph));

    double weightEdge = weight[eCur];

    //check if output graph already has the input vertex
    te::graph::Vertex* vFrom = graphOut->getVertex(vertexSourceId);

    if(!vFrom)
    {
      vFrom = new te::graph::Vertex(m_inputGraph->getVertex(vertexSourceId));

      vFrom->getNeighborhood().clear();
      vFrom->getPredecessors().clear();
      vFrom->getSuccessors().clear();
      
      graphOut->add(vFrom);
    }

    //check if output graph already has the output vertex
    te::graph::Vertex* vTo = graphOut->getVertex(vertexTargetId);

    if(!vTo)
    {
      vTo = new te::graph::Vertex(m_inputGraph->getVertex(vertexTargetId));

      vTo->getNeighborhood().clear();
      vTo->getPredecessors().clear();
      vTo->getSuccessors().clear();

      graphOut->add(vTo);
    }

    //create edge
    te::graph::Edge* e = new te::graph::Edge((int)t, vertexSourceId, vertexTargetId);

    e->setAttributeVecSize(size);
    e->addAttribute(edgeWeightIdx, new te::dt::SimpleData<double, te::dt::DOUBLE_TYPE>(weightEdge));

    graphOut->add(e);
  }

  return graphOut;
}

te::graph::AbstractGraph* te::sa::MinimumSpanningTree::createGraph()
{
// graph type
  std::string graphType = te::graph::Globals::sm_factoryGraphTypeUndirectedGraph;

// connection info
  const std::string connInfo("memory:");

// graph information
  std::map<std::string, std::string> graphInfo;
  graphInfo["GRAPH_DATA_SOURCE_TYPE"] = "MEM";
  graphInfo["GRAPH_NAME"] = "mst_graph";
  graphInfo["GRAPH_DESCRIPTION"] = "Generated by Minimum Spanning Tree.";

  //create output graph
  te::graph::AbstractGraph* graph = te::graph::AbstractGraphFactory::make(graphType, connInfo, graphInfo);

  //copy vertex properties from gpm graph
  for(int i = 0; i < m_inputGraph->getMetadata()->getVertexPropertySize(); ++i)
  {
    te::dt::Property* p = m_inputGraph->getMetadata()->getVertexProperty(i)->clone();
    
    p->setParent(nullptr);

    graph->getMetadata()->addVertexProperty(p);
  }

  return graph;
}