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/*PGR-GNU*****************************************************************
File: pgr_randomSpanningTree.hpp
Copyright (c) 2018-2026 pgRouting developers
Mail: project@pgrouting.org
Copyright (c) 2018 Aditya Pratap Singh
adityapratap.singh28@gmail.com
------
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
********************************************************************PGR-GNU*/
#ifndef INCLUDE_SPANNINGTREE_PGR_RANDOMSPANNINGTREE_HPP_
#define INCLUDE_SPANNINGTREE_PGR_RANDOMSPANNINGTREE_HPP_
#pragma once
#include <vector>
#include <random>
#include <iostream>
#include <exception>
#include <boost/config.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/random_spanning_tree.hpp>
#include <boost/random/random_number_generator.hpp>
#include <boost/graph/graph_traits.hpp>
#include "cpp_common/path.hpp"
#include "cpp_common/pgr_base_graph.hpp"
#include "cpp_common/interruption.hpp"
template < class G > class Pgr_randomSpanningTree;
// user's functions
// for development
//******************************************
template < class G >
class Pgr_randomSpanningTree {
public:
typedef typename G::V V;
typedef typename G::E E;
std::vector<SpanTree_rt> randomSpanningTree(
G &graph,
int64_t root_vertex);
private:
// Member
std::vector< V > predecessors;
// Function
std::vector< SpanTree_rt >
undirectedGraph(
const G &graph,
int64_t root_vertex) {
std::ostringstream log;
auto v_root(graph.get_V(root_vertex));
std::minstd_rand rng;
/* abort in case of an interruption occurs (e.g. the query is being cancelled) */
CHECK_FOR_INTERRUPTS();
// TODO(aps)
// This function is running in infinite loop
try {
boost::random_spanning_tree(
graph.graph,
rng,
boost::root_vertex(v_root)
.predecessor_map(&predecessors[0])
.weight_map(get(&G::G_T_E::cost, graph.graph)));
} catch (std::exception const &ex) {
log << ex.what();
} catch (...) {
log << "Unknown exception caught";
}
std::vector< SpanTree_rt > result;
return result;
#if 0
std::vector< SpanTree_rt > results;
double totalcost = 0;
SpanTree_rt tmp;
tmp.root_vertex = root_vertex;
tmp.edge = -1;
tmp.cost = 0;
tmp.tree_cost = totalcost;
results.push_back(tmp);
for (size_t j = 0; j < predecessors.size(); j++) {
if (j != v_root) {
SpanTree_rt tmp;
auto start_node = graph.graph[predecessors[j]].id;
auto end_node = graph.graph[j].id; // node
auto v_sn(graph.get_V(start_node));
auto v_en(graph.get_V(end_node));
auto cost = graph[boost::edge(
predecessors[j], j, graph.graph).first].cost;
auto edge_id =
graph.get_edge_id(v_sn, v_en, cost);
totalcost += cost;
tmp.root_vertex = root_vertex;
tmp.edge = edge_id; // edge_id
tmp.cost = cost; // cost
tmp.tree_cost = totalcost; // tree_cost
results.push_back(tmp);
}
}
return results;
}
#endif
};
template < class G >
std::vector<SpanTree_rt>
Pgr_randomSpanningTree< G >::randomSpanningTree(
G &graph,
int64_t root_vertex ) {
predecessors.clear();
// TODO(aps)
// Currently only running for undirected graph
return undirectedGraph(
graph,
root_vertex);
}
#endif // INCLUDE_SPANNINGTREE_PGR_RANDOMSPANNINGTREE_HPP_
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