如何使用Boost图形库更改图中的边权重

How do I change the edge weight in a graph using the Boost Graph Library?

本文关键字：权重 何使用 Boost 图形库      更新时间：2023-10-16

我已经使用Boost图形库定义了一个图形，

typedef boost::property<boost::edge_weight_t, int> EdgeWeightProperty;
typedef boost::adjacency_list<boost::listS, boost::vecS,boost::undirectedS,boost::no_property,EdgeWeightProperty> Graph;

使用

添加边是相当简单的
boost::add_edge(vertice1, vertice2, weight, graph);

我还没有弄清楚如何改变边的权重，一旦它已经设置。一种可能的解决方案是删除边缘并重新添加更新的权重值，然而，这似乎有点过度。

一个解决方案是执行以下操作

typedef boost::adjacency_list<boost::setS, boost::vecS, boost::undirectedS,boost::no_property,EdgeWeightProperty> Graph;
typedef Graph::edge_descriptor Edge;
Graph g;
std::pair<Edge, bool> ed = boost::edge(v1,v2,g);
int weight = get(boost::edge_weight_t(), g, ed.first);
int weightToAdd = 10;
boost::put(boost::edge_weight_t(), g, ed.first, weight+weightToAdd);

另一种解决方案是使用属性映射。下面是一个例子。

// Edge weight.
typedef boost::property<boost::edge_weight_t, int> EdgeWeightProperty;
// Graph.
typedef boost::adjacency_list< boost::listS,
                               boost::vecS,
                               boost::undirectedS,
                               boost::no_property,
                               EdgeWeightProperty > Graph;
// Vertex descriptor.
typedef typename boost::graph_traits<Graph>::vertex_descriptor Vertex;
// The Graph object
Graph g;
// Populates the graph.
Vertex v1 = boost::add_vertex(g);
Vertex v2 = boost::add_vertex(g);
Vertex v3 = boost::add_vertex(g);
boost::add_edge(v1, v2, EdgeWeightProperty(2), g);
boost::add_edge(v1, v3, EdgeWeightProperty(4), g);
boost::add_edge(v2, v3, EdgeWeightProperty(5), g);
// The property map associated with the weights.
boost::property_map < Graph,
                      boost::edge_weight_t >::type EdgeWeightMap = get(boost::edge_weight, g);
// Loops over all edges and add 10 to their weight.
boost::graph_traits< Graph >::edge_iterator e_it, e_end;
for(std::tie(e_it, e_end) = boost::edges(g); e_it != e_end; ++e_it)
{
  EdgeWeightMap[*e_it] += 10;
}
// Prints the weighted edgelist.
for(std::tie(e_it, e_end) = boost::edges(g); e_it != e_end; ++e_it)
{
  std::cout << boost::source(*e_it, g) << " "
            << boost::target(*e_it, g) << " "
            << EdgeWeightMap[*e_it] << std::endl;
}
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