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/*PGR-GNU*****************************************************************
File: prim.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_PRIM_HPP_
#define INCLUDE_SPANNINGTREE_PRIM_HPP_
#pragma once
#include <vector>
#include <set>
#include <cstdint>
#include <visitors/prim_dijkstra_visitor.hpp>
#include <boost/graph/prim_minimum_spanning_tree.hpp>
#include "spanningTree/mst.hpp"
#include "cpp_common/interruption.hpp"
//******************************************
namespace pgrouting {
namespace functions {
template <class G>
class Pgr_prim : public Pgr_mst<G> {
typedef typename G::V V;
typedef typename G::E E;
typedef typename G::B_G B_G;
public:
virtual ~Pgr_prim() = default;
std::vector<MST_rt> prim(G &graph);
std::vector<MST_rt> primBFS(
G &graph,
std::vector<int64_t> roots,
int64_t max_depth);
std::vector<MST_rt> primDFS(
G &graph,
std::vector<int64_t> roots,
int64_t max_depth);
std::vector<MST_rt> primDD(
G &graph,
std::vector<int64_t> roots,
double distance);
private:
// Functions
void clear() {
data.clear();
predecessors.clear();
distances.clear();
}
void primTree(
const G &graph,
int64_t root_vertex);
void generate_mst(const G &graph);
private:
// Member
std::vector<V> predecessors;
std::vector<double> distances;
std::vector<V> data;
std::set<V> m_unassigned;
};
template <class G>
void
Pgr_prim<G>::primTree(
const G &graph,
int64_t root_vertex) {
clear();
predecessors.resize(graph.num_vertices());
distances.resize(graph.num_vertices());
auto v_root(graph.get_V(root_vertex));
using prim_visitor = visitors::Prim_dijkstra_visitor<V>;
/* abort in case of an interruption occurs (e.g. the query is being cancelled) */
CHECK_FOR_INTERRUPTS();
boost::prim_minimum_spanning_tree(
graph.graph,
&predecessors[0],
boost::distance_map(&distances[0]).
weight_map(get(&G::G_T_E::cost, graph.graph))
.root_vertex(v_root)
.visitor(prim_visitor(data)));
for (const auto v : data) {
/*
* its not a tree, its a forest
* - v is not on current tree
*/
if (std::isinf(distances[v])) continue;
m_unassigned.erase(v);
auto u = predecessors[v];
/*
* Not a valid edge
*/
if (u == v) continue;
auto cost = distances[u] - distances[v];
auto edge = graph.get_edge(u, v, cost);
this->m_spanning_tree.edges.insert(edge);
}
}
template <class G>
void
Pgr_prim<G>::generate_mst(const G &graph) {
this->clear();
size_t totalNodes = num_vertices(graph.graph);
m_unassigned.clear();
for (V v = 0; v < totalNodes; ++v) {
m_unassigned.insert(m_unassigned.end(), v);
}
while (!m_unassigned.empty()) {
auto root = *m_unassigned.begin();
m_unassigned.erase(m_unassigned.begin());
primTree(
graph,
graph.graph[root].id);
}
}
template <class G>
std::vector<MST_rt>
Pgr_prim<G>::prim(
G &graph) {
return this->mst(graph);
}
template <class G>
std::vector<MST_rt>
Pgr_prim<G>::primBFS(
G &graph,
std::vector<int64_t> roots,
int64_t max_depth) {
return this->mstBFS(graph, roots, max_depth);
}
template <class G>
std::vector<MST_rt>
Pgr_prim<G>::primDFS(
G &graph,
std::vector<int64_t> roots,
int64_t max_depth) {
return this->mstDFS(graph, roots, max_depth);
}
template <class G>
std::vector<MST_rt>
Pgr_prim<G>::primDD(
G &graph,
std::vector<int64_t> roots,
double distance) {
return this->mstDD(graph, roots, distance);
}
} // namespace functions
} // namespace pgrouting
#endif // INCLUDE_SPANNINGTREE_PRIM_HPP_
|
