fastest path between more than two nodes

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Salah Gohar
Salah Gohar on 18 Nov 2021
Commented: Christine Tobler on 18 Nov 2021
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?
  2 Comments
Christine Tobler
Christine Tobler on 18 Nov 2021
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
Salah Gohar on 18 Nov 2021
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!

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Answers (1)

Christine Tobler
Christine Tobler on 18 Nov 2021
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
  2 Comments
Salah Gohar
Salah Gohar on 18 Nov 2021
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
Christine Tobler on 18 Nov 2021
You need to use a for-loop and call shortestpath with just one node at a time, like in the code I added above.

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