Find the farthest point on the graph

[Chintan Pathak]

Dear all,

I want to try to find the point on my road graph, that is farthest from a particular point. This works well once but not the second time. The image attached shows the problem, and the attached code shows some things I have attempted.

I tried to use "first(road_network.vertices)" and "farthest_to", but they both give me answers other than the one expected. I also tried clean_network, but that did not help either.

Any guidance in this regards would be helpful.

Thanks
Chintan Pathak

[Kevin Chapuis]

Dear Chintan Pathak,

This is not clear to me what you trying to achieve. If by "farthest" point from a particular point means the longest shortest path from this point to any other destination on the network, there is a workaround collecting each shortest path starting from this point and picking the longest one. As far as I can tell, the "farthest_to" operator pick the farthest point in the continuous space, not using network topology.

Best,

Kevin

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Chapuis kevin
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IRD, UMI 209 UMMISCO

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[Chintan Pathak]

Dear Kevin,

Thank you for your response. Your suggested workaround works for me, I am just surprised why farthest_to wouldnt work. It works once in one direction.

For record, I am doing the following:
verts <- road_network.vertices;
loop iii from: 0 to: length(verts) - 1 {
add distance_to(verts[iii], pt_ft_cs[0]) to: distances;
}
ind <- index_of(distances, max(distances));
// ind contains the index of the vertex that is farthest from pt_ft_cs[0]

Thanks

[Chintan Pathak]

Just realized my mistake, the 'farthest_to' statement should be inside 'using topology'. It works fine now.

Thanks


On Tuesday, January 22, 2019 at 7:35:41 PM UTC-8, Kevin Chapuis wrote: