Hi
>From what I understand of Dijkstras search, Dijkstras visitor is invoked at
traversal of a vertex. However, this is still separate from the weights
which is a required argument the algorithm takes. In my case however, the
weight of traversing the edge is a function of cost of traversing to the
edge from the origin vertex.
I just used cost * weight as an example. In the actual algorithm,
weight(edge) = interval_search(cost(edge[origin_vertex] ), interval_map)
On Sep 18, 2014 7:01 PM, "Tiago Peixoto [via Main discussion list for the
graph-tool project]" <[email protected]> wrote:
> On 18.09.2014 11:42, ambasta wrote:
>
> > Hi,
> >
> > I have two problems
> >
> > class Weights:
> > ...
> >
> >
> > g = Graph(directed=True)
> > weights = g.new_edge_property('object')
> >
> > vertex_one = g.add_vertex()
> > vertex_two = g.add_vertex()
> > edge = g.add_edge(vertex_one, vertex_two)
> > weights[edge] = Weights(1)
> >
> > g.shortest_path(vertex_one, vertex_two, weights)
> >
> > This raises ValueError: property map 'dist_map' is not of scalar type.
> Is
> > there a function I can implement in Weights for it to return a scalar
> value
> > to be used during calculation of shortest path.
> Take a look at the search module:
>
> https://graph-tool.skewed.de/static/doc/search_module.html
>
> You should use the dijkstra_search() function, and specialize the
> DijkstraVisitor class to do what you want.
>
>
> > Secondly, consider a directed graph where the edge weight is a function
> of
> > cost at edge's origin vertex, i.e. the weight class is defined as:
> >
> > class Weights:
> > ....
> > def get_weight(current_cost):
> > return self.cost * current_cost
> >
> >
> > Hence during calculation of shortest_path/distance, is it possible to
> pass
> > the weight at the traversed/visited edge to get the cost of the edge.
> You can do that with the dijkstra_search() function, as I mentioned
> above. However, note that multiplying weights is the same as summing
> their logarithms... Hence you could simply use the log of the weights
> instead, and save you some trouble.
>
> Best,
> Tiago
>
>
> --
> Tiago de Paula Peixoto <[hidden email]
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