fastest path between more than two nodes

I have a table of 217 node and i want to compute the fastestpath between only 20 node which called OD.

i have also a column which define these OD nodes from 1 to 20 and the other nodes are 0.

how can i write this code ; ”0” = no ShortestPath Calc; otherwise OD node?

[Christine Tobler]

It looks like you have a set of nodes with X and Y coordinates, but not connectivity information between them (edges connecting pairs of nodes with each other).

What is the shortest path you're trying to compute? Is it the distance between two nodes when connected by a straight line, or some other thing?

[Salah Gohar]

i have also the connectivity information and i already wrote the code for the Graph.

i tried this code to define the 20 OD node:

v=1

for i=1:217

if ODnode(i) ~= 0

OD(v) = ODnode(i);

i_no(v)=i;

v= v+1;

end

end

OD

i_no

i need now to get the shortest path between all the 20 ODnodes!

Answer 1

[Christine Tobler]

To compute simply the shortest-path distance, you can use the distances function and pass in a graph object you've constructed using the connectivity information, and the OD vector you constructed above.

If you need the paths, you will need a for-loop:

for i=1:length(OD)
    for j = 1:length(OD)
        paths{i, j} = shortestpath(G, OD(i), OD(j));
    end
end

[Salah Gohar]

Error using graph/shortestpath (line 57)

Source must specify one node.

i have now a 20 by 20 MAtrix ,how can i get the shortestpath between them all?

[Christine Tobler]

You need to use a for-loop and call shortestpath with just one node at a time, like in the code I added above.