5

I am investigating the use of the boost graph libraries in order to apply them to various network problems I have in mind.

In the examples I have been looking at the graph edge values ("weights") are always initialized as integers, such as in these Bellman-Ford and Kruskal algorithms eg:

int weights[] = { 1, 1, 2, 7, 3, 1, 1, 1 };

My problem is if I try and change the weights to double, I get a heap of warning messages about conversions etc, which so far I have not been able to figure out how to overcome.

Does anyone see a way around this?

Flexo
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AndyUK
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1 Answers1

6

It's caused by a mismatch between the weights[] array and the type used for edge weights by your boost graph/algorithm.

In the first linked sample, eg, you should also change

struct EdgeProperties {
  int weight;
};
[...]
property_map<Graph, int EdgeProperties::*>::type

to

struct EdgeProperties {
  double weight;
};
[...]
property_map<Graph, double EdgeProperties::*>::type

In the second

typedef adjacency_list < vecS, vecS, undirectedS,
    no_property, property < edge_weight_t, int > > Graph;

to

typedef adjacency_list < vecS, vecS, undirectedS,
    no_property, property < edge_weight_t, double > > Graph;
baol
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  • Hi the code can be seen in those links: bellman-example.cpp and kruskal-example.cpp – AndyUK Apr 09 '10 at 15:03
  • Your suggestion for the second (Kruskal) has worked, cheers. I cannot quite get over the Bellman hurdle yet. – AndyUK Apr 09 '10 at 15:17
  • In the bellman example you also need to change the type of the property map for the edges. Bundled properties are my favorite way to use the BGL (http://www.boost.org/doc/libs/1_42_0/libs/graph/doc/bundles.html). – baol Apr 09 '10 at 15:53