I want to use boost's dijkstra algorithm (since I'm using boost in other parts of my program). The problem I'm having is adding custom objects (I believe they are referred to as property) to the adjacency_list.
Essentially I have a custom edge class that maintains all sorts of information regarding the edge and the vertices that are connected through it. I want to store my custom data object with the edge properties that are required by the adjaceny_list
I've successfully implemented the toy example that boost provides. I've tried to use custom properties to no avail (boost example, boost properties). I'm fine with just encapsulating my VEdge data structure in a struct or something, I just need to be able to retrieve it. But I haven't been able to figure out how to include my custom data structure into the boost adjaceny_list structure.
In my case I have the following program:
Main.cpp:
#include <iostream>
#include <fstream>
#include "dijkstra.h"
#include <vector>
int
main(int, char *[])
{
// Generate the vector of edges from elsewhere in the program
std::vector<VEdge*> edges; //someclass.get_edges();
td* test = new td(edges);
test->run_d();
test->print_path();
return EXIT_SUCCESS;
}
Dijkstra.cpp:
#include <iostream>
#include <fstream>
#include "dijkstra.h"
using namespace boost;
td::td() {
kNumArcs = sizeof(kEdgeArray) / sizeof(Edge);
kNumNodes = 5;
}
td::td(std::vector<VEdge*> edges) {
// add edges to the edge property here
for(VEdge* e : edges) {
// for each edge, add to the kEdgeArray variable in some way
// The boost example forces the input to be an array of edge_property type.
// So here is where I will convert my raw VEdge data structure to
// the custom edge_property that I am struggling to understand how to create.
}
kNumArcs = sizeof(kEdgeArray) / sizeof(Edge);
kNumNodes = 5;
}
void td::run_d() {
kGraph = graph_t(kEdgeArray, kEdgeArray + kNumArcs, kWeights, kNumNodes);
kWeightMap = get(edge_weight, kGraph);
kP = std::vector<vertex_descriptor >(num_vertices(kGraph));
kD = std::vector<int>(num_vertices(kGraph));
kS = vertex(A, kGraph);
dijkstra_shortest_paths(kGraph, kS,
predecessor_map(boost::make_iterator_property_map(kP.begin(), get(boost::vertex_index, kGraph))).
distance_map(boost::make_iterator_property_map(kD.begin(), get(boost::vertex_index, kGraph))));
}
void td::print_path() {
std::cout << "distances and parents:" << std::endl;
graph_traits < graph_t >::vertex_iterator vi, vend;
for (boost::tie(vi, vend) = vertices(kGraph); vi != vend; ++vi) {
std::cout << "distance(" << kName[*vi] << ") = " << kD[*vi] << ", ";
std::cout << "parent(" << kName[*vi] << ") = " << kName[kP[*vi]] << std::
endl;
}
}
void td::generate_dot_file() {
std::cout << std::endl;
std::ofstream dot_file("figs/dijkstra-eg.dot");
dot_file << "digraph D {\n"
<< " rankdir=LR\n"
<< " size=\"4,3\"\n"
<< " ratio=\"fill\"\n"
<< " edge[style=\"bold\"]\n" << " node[shape=\"circle\"]\n";
graph_traits < graph_t >::edge_iterator ei, ei_end;
for (boost::tie(ei, ei_end) = edges(kGraph); ei != ei_end; ++ei) {
graph_traits < graph_t >::edge_descriptor e = *ei;
graph_traits < graph_t >::vertex_descriptor
u = source(e, kGraph), v = target(e, kGraph);
dot_file << kName[u] << " -> " << kName[v]
<< "[label=\"" << get(kWeightMap, e) << "\"";
if (kP[v] == u)
dot_file << ", color=\"black\"";
else
dot_file << ", color=\"grey\"";
dot_file << "]";
}
dot_file << "}";
}
Dijkstra.h:
#ifndef _TEMPD_H_
#define _TEMPD_H_
#pragma once
#include <boost/config.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/dijkstra_shortest_paths.hpp>
#include <boost/property_map/property_map.hpp>
using namespace boost;
typedef adjacency_list < listS, vecS, directedS,
no_property, property < edge_weight_t, int > > graph_t;
typedef graph_traits < graph_t >::vertex_descriptor vertex_descriptor;
typedef std::pair<int, int> Edge;
struct VEdge{
// custom variables here
VNode start;
VNode end;
int weight;
int id;
// other irrelevant data pertinent to my program that must be preserved
};
struct VNode {
// custom variables here
int x;
int y;
int id;
// other irrelevant data pertinent to my program that must be preserved
}
enum nodes { A, B, C, D, E };
class td {
public:
td();
td(std::vector<VEdge*>);
~td();
void run_d();
void print_path();
void generate_dot_file();
private:
Edge kEdgeArray[9] = { Edge(A, C), Edge(B, B), Edge(B, D), Edge(B, E),
Edge(C, B), Edge(C, D), Edge(D, E), Edge(E, A), Edge(E, B)
};
char kName[5] = {'A','B','C','D','E'};
int kWeights[9] = { 1, 2, 1, 2, 7, 3, 1, 1, 1 };
int kNumArcs;
int kNumNodes;
vertex_descriptor kS;
graph_t kGraph;
std::vector<int> kD;
std::vector<vertex_descriptor> kP;
property_map<graph_t, edge_weight_t>::type kWeightMap;
};
#endif
I know my example is a bit contrived, but it communicates what I'm trying to accomplish. I know I need a custom data structure for my edge_descriptor which gets sent to the graph_t typedef.
So I'm looking to alter my Dijkstra.h file to look something like this:
struct vertex_label_t {vertex_property_tag kind;};
struct edge_label_t {edge_property_tag kind;};
typedef property <vertex_custom_t, VNode*>,
property <vertex_label_t, string>,
property <vertex_root_t, ing> > > vertex_p;
typedef property <edge_custom_t, VEdge*>,
property <edge_label_t, string > > edge_p;
typedef adjacency_list < listS, vecS, directedS,
vertex_p, edge_p > graph_t;
typedef graph_traits < graph_t >::vertex_descriptor vertex_descriptor;
VEdgeis an empty struct, and not even the comments make it clear how they would refer to the vertices they connect. – Electorstd::pair<int, int>property in a way that my VEdge struct would be part of that property that is passed to the adjacency_list. – HarbotVEdge*elements. Please, simply elaborate on that. Perhaps, remove the unrelated demo code. – Elector