[英]What is a Simple Example for using the Boost Graph Library
I am trying to use theBGL , I find the documentation precise but lacks more examples for simple cases.我正在尝试使用BGL ,我发现文档很准确,但缺少更多简单案例的示例。 My goal is described below (after reading the documentation I still couldn't do this):
我的目标如下所述(阅读文档后我仍然无法做到这一点):
struct Vertex
{
double m_d;
std::size_t m_id;
};
//or
struct Vertex
{
double m_d;
std::size_t id() const;
};
Goals :目标:
Could you please write me an example on how to do this with BGL please?你能给我写一个关于如何用 BGL 做到这一点的例子吗? I beleive I need
MutableBidirectionalGraph
?我相信我需要
MutableBidirectionalGraph
?
A directed graph
G
有向图
G
Straight-away:马上:
struct Vertex { double m_d = 0; size_t m_id = -1; // or std::size_t id() const; }; struct Edge { double cost = 0; }; using Graph = boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, Vertex, Edge>;
(what is the difference between a bidirectional and directed other than
in_edges
please?)(除了
in_edges
之外,双向和定向之间有什么区别?)
There is no other difference, except of course the complexity guarantees for enumerating incoming edges, and a linear overhead upon insertion of edges没有其他区别,当然除了枚举传入边的复杂性保证以及插入边时的线性开销
G
can hold the vertex typeVertex
.G
可以保存顶点类型Vertex
。
See 0.见 0。
get the vertex by id from
G
从
G
中通过 id 获取顶点
auto find_by_id = [&g](size_t id) -> Vertex& { auto vv = boost::make_iterator_range(vertices(g)); auto vd = find_if(vv, [&, id](auto vd) { return g[vd].m_id == id; }); return g[*vd]; };
and change the value
m_d
in theVertex
struct when I want.并在需要时更改
Vertex
结构中的值m_d
。
if (i_want()) { g[vd].m_id += 1; }
Or,要么,
auto idmap = boost::get(&Vertex::m_id, g); if (i_want()) { idmap[vd] += 1; }
or even甚至
put(idmap, vd, 42);
or even more unmarked:甚至更多未标记:
get(boost::vertex_bundle, g, vd).m_id = 999;
add, remove vertices
添加、删除顶点
remove_vertex(vd, g);
and edges between vertices
和顶点之间的边
clear_vertex(vd, g);
and also supports costs ie cost(edge).
并且还支持成本,即成本(边缘)。
Wow that really has nothing to do with any of the above.哇,这真的与以上任何一项都无关。 But it's really the same as with vertex ids:
但它实际上与顶点 ID 相同:
if (i_want()) { g[ed].cost = new_cost; }
Or,要么,
auto cost = boost::get(&Edge::cost, g); if (i_want()) { cost[ed] = new_cost; }
or even甚至
put(cost, ed, new_cost);
or even more unmarked:甚至更多未标记:
get(boost::edge_bundle, g, ed).cost = new_cost;
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/graph_utility.hpp>
#include <boost/range/algorithm.hpp>
#include <iostream>
struct Vertex {
double m_d = 0;
size_t m_id = -1;
// or std::size_t id() const;
};
struct Edge {
double cost = 0;
};
using Graph =
boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, Vertex, Edge>;
using boost::make_iterator_range;
int main(){
Graph g;
auto v0 = add_vertex({0.1, 100}, g);
auto v1 = add_vertex({0.2, 200}, g);
auto v2 = add_vertex({0.3, 300}, g);
auto v3 = add_vertex({0.4, 400}, g);
auto v4 = add_vertex({0.5, 500}, g);
auto v5 = add_vertex({0.6, 600}, g);
add_edge(v0, v2, Edge{1.5}, g);
add_edge(v1, v3, Edge{2.5}, g);
add_edge(v4, v1, Edge{3.5}, g);
add_edge(v2, v5, Edge{4.5}, g);
auto idmap = boost::get(&Vertex::m_id, g);
auto cost = boost::get(&Edge::cost, g);
auto find_by_id = [&g](size_t id) -> Vertex& {
auto vv = boost::make_iterator_range(vertices(g));
auto vd = find_if(vv, [&, id](auto vd) { return g[vd].m_id == id; });
return g[*vd];
};
print_graph(g, idmap, std::cout << "original: ");
auto i_want = [](auto vd) {
return (vd % 2); // when I want
};
for (auto vd : make_iterator_range(vertices(g))) {
if (i_want(vd))
g[vd].m_id += 1;
if (i_want(vd))
idmap[vd] += 1;
//put(idmap, vd, 42);
//get(boost::vertex_bundle, g, vd).m_id = 999;
}
print_graph(g, idmap, std::cout << "altered: ");
clear_vertex(v3, g);
remove_vertex(v3, g); // undefined behaviour unless edges cleared
print_graph(g, idmap, std::cout << "removed: ");
for (auto ed : make_iterator_range(edges(g))) {
std::cout << ed << " cost " << cost[ed] << "\n";
}
for (auto ed : make_iterator_range(edges(g))) {
cost[ed] *= 111;
}
for (auto ed : make_iterator_range(edges(g))) {
std::cout << ed << " cost " << cost[ed] << "\n";
}
};
Prints印刷
original: 100 --> 300
200 --> 400
300 --> 600
400 -->
500 --> 200
600 -->
altered: 100 --> 300
202 --> 402
300 --> 602
402 -->
500 --> 202
602 -->
removed: 100 --> 300
202 -->
300 --> 602
500 --> 202
602 -->
(0,2) cost 1.5
(3,1) cost 3.5
(2,4) cost 4.5
(0,2) cost 166.5
(3,1) cost 388.5
(2,4) cost 499.5
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