Algorithm 如何使用get()boost图
我正在尝试实现我自己的A星算法。然而,我只找到了一种通过迭代器获得边权重值的方法。由于迭代器按顺序访问属性映射,因此我无法对边进行优先级排序,需要对每个顶点进行完整循环以找到邻居,这将使算法非常缓慢 有没有办法使用get(),put()。。。如果没有迭代器,选择要检查其边的顶点 这是我目前的计划:Algorithm 如何使用get()boost图,algorithm,boost,graph,a-star,boost-graph,Algorithm,Boost,Graph,A Star,Boost Graph,我正在尝试实现我自己的A星算法。然而,我只找到了一种通过迭代器获得边权重值的方法。由于迭代器按顺序访问属性映射,因此我无法对边进行优先级排序,需要对每个顶点进行完整循环以找到邻居,这将使算法非常缓慢 有没有办法使用get(),put()。。。如果没有迭代器,选择要检查其边的顶点 这是我目前的计划: struct Point {//struct point with vertex properties int x, y; int parentx, parenty; doub
struct Point {//struct point with vertex properties
int x, y;
int parentx, parenty;
double g;
double h;
friend std::ostream& operator<<(std::ostream& os, Point p) {
return os << "[" << p.x << "," << p.y << "]";
}
};
int main() {
//declarations
typedef property < edge_weight_t, double >Weight;
using std::vector;//?
using Graph = adjacency_list<setS, vecS, undirectedS, Point, Weight>;//graph includes our created point struct property<edge_weight_t
using vertex_descriptor = Graph::vertex_descriptor;
Graph lattuce;
//lattuce graph is created with weighted edges value 1 or 1,41 if diagonal. The functions used on a loop are:
//add_edge(nodes[p.x][p.y],nodes[neighbour.x][neighbour.y], Weight(1.0), lattuce);
//add_edge(nodes[p.x][p.y],nodes[neighbour.x][neighbour.y], Weight(1.4), lattuce);
typedef Graph::edge_iterator EdgeIterator;
std::pair<EdgeIterator, EdgeIterator> edges = boost::edges(lattuce);
typedef boost::property_map<Graph, boost::edge_weight_t>::type WeightMap;
WeightMap weights = boost::get(boost::edge_weight_t(), lattuce);
//cout<<get(weights,(1,2));
EdgeIterator edge;
for (edge = edges.first; edge != edges.second; ++edge) {
std::cout << boost::get(weights, *edge) <<" "<< *edge<< " ";
if (source(*edge, lattuce) == origin || target(*edge, lattuce)==origin ){
get(weights, *edge);
cout<<"Edge related to the origin ";
}
if (source(*edge, lattuce) == end_vertex || target(*edge, lattuce)==end_vertex ){
cout<<"Edge related to the end_vertex ";
}
if (get(weights, *edge)==1.41){
cout<<" Diagonal"<<endl;
}
else if (get(weights, *edge)==1){
cout<<" Unitary"<<endl;
}
else if (get(weights, *edge)==99999999.0){
cout<<"Infinite"<<endl;
}
}
}
struct Point{//具有顶点属性的struct Point
int x,y;
int parentx,parenty;
双g;
双h;
friend std::ostream&Operator回答您的问题
您可以使用顶点描述符而不是迭代器
在您的情况下,因为您使用的是捆绑属性,所以可以在图形上使用操作符[descriptor]
速记
只要图形不是常量,就可以使用它来更改绑定的属性
密码
实际上,我并不清楚你问题中的代码应该说明什么。我将简单地用一段类似的分离代码来回答,它是从那里构建的,并向你展示了一些可能很有启发性的东西:)
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/astar_search.hpp>
#include <boost/graph/random.hpp>
#include <iostream>
#include <random>
static std::mt19937 s_rng { std::random_device{}() };
static std::uniform_int_distribution<> s_coord(-10,10);
static std::uniform_real_distribution<double> s_double(-1.,1.);
static int gen_coord() { return s_coord(s_rng); }
static int gen_gh () { return s_double(s_rng); }
struct Point { // struct point with vertex properties
int x = gen_coord(), y = gen_coord();
int parentx = gen_coord(), parenty = gen_coord();
double g = gen_gh();
double h = gen_gh();
friend std::ostream &operator<<(std::ostream &os, Point p) { return os << "[" << p.x << "," << p.y << "]"; }
};
// declarations
typedef boost::property<boost::edge_weight_t, double> Weight;
using Graph = boost::adjacency_list<boost::setS, boost::vecS, boost::undirectedS, Point, Weight>;
using vertex_descriptor = Graph::vertex_descriptor;
int main() {
Graph lattuce;
using namespace boost;
generate_random_graph(lattuce, 10, 20, s_rng);
vertex_descriptor origin = vertex(0, lattuce);
vertex_descriptor end_vertex = vertex(9, lattuce);
typedef boost::property_map<Graph, boost::edge_weight_t>::type WeightMap;
WeightMap weights = boost::get(boost::edge_weight_t(), lattuce);
for (Graph::edge_descriptor edge : make_iterator_range(edges(lattuce))) {
std::cout << boost::get(weights, edge) << " " << edge << " ";
vertex_descriptor src = source(edge, lattuce);
vertex_descriptor trg = target(edge, lattuce);
Point& src_bundle = lattuce[src];
Point& trg_bundle = lattuce[trg];
std::cout << "Edge: " << src_bundle << " -- " << trg_bundle << "\n";
src_bundle.g *= 1.1;
src_bundle.h *= -1.1;
//double weight = get(weights, edge);
}
(void) origin; // unused
(void) end_vertex; // unused
}
哇,谢谢你,这个答案帮了我很多:D。只有一个问题,for循环中的条件是什么?@AMartin它是一个范围for循环,所以没有(显式)循环条件。你可以使用BGL\u来处理所有边(边、板条、图形)
和boost/Graph/iteration\u宏。hpp
和c++03
0 (7,5) Edge: [-5,-5] -- [-9,-6]
0 (9,2) Edge: [3,2] -- [-3,3]
0 (3,4) Edge: [-4,-10] -- [-10,-5]
0 (1,6) Edge: [3,4] -- [-7,7]
0 (9,4) Edge: [3,2] -- [-10,-5]
0 (3,8) Edge: [-4,-10] -- [-6,0]
0 (1,9) Edge: [3,4] -- [3,2]
0 (5,9) Edge: [-9,-6] -- [3,2]
0 (6,9) Edge: [-7,7] -- [3,2]
0 (0,1) Edge: [-9,8] -- [3,4]
0 (1,4) Edge: [3,4] -- [-10,-5]
0 (0,2) Edge: [-9,8] -- [-3,3]
0 (9,3) Edge: [3,2] -- [-4,-10]
0 (2,4) Edge: [-3,3] -- [-10,-5]
0 (7,6) Edge: [-5,-5] -- [-7,7]
0 (1,2) Edge: [3,4] -- [-3,3]
0 (0,9) Edge: [-9,8] -- [3,2]
0 (4,7) Edge: [-10,-5] -- [-5,-5]
0 (1,5) Edge: [3,4] -- [-9,-6]
0 (0,7) Edge: [-9,8] -- [-5,-5]