Clear Filters
Clear Filters

Using accumarray to sum all values associated with a given node

1 view (last 30 days)
Given a graph with the following edges
edges = [1 2; 2 3; 3 1; 2 4; 4 5; 4 1];
I have some data associated with each edge
data=[0.276
0.679
0.655
0.162
0.118
0.333];
For a given node, I want to sum the data values corresponding to all edges it's connected to. How do I do this? accumarray looks promising, but this gives six nonzero values, when there should just be 5 (and I don't know how to distinguish which one corresponds to which node).
sum_data = accumarray(edges,data);

Accepted Answer

Matt J
Matt J on 22 Jan 2024
Edited: Matt J on 22 Jan 2024
One way:
edges = [1 2; 2 3; 3 1; 2 4; 4 5; 4 1];
data=[0.276
0.679
0.655
0.162
0.118
0.333];
G=graph(edges(:,1), edges(:,2), data);
out=sum(adjacency(G,'weighted'),2)
out =
(1,1) 1.2640 (2,1) 1.1170 (3,1) 1.3340 (4,1) 0.6130 (5,1) 0.1180
  4 Comments
L'O.G.
L'O.G. on 22 Jan 2024
Ah ok, I was just wondering if I could've used accumarray after all. Thank you!
Matt J
Matt J on 22 Jan 2024
Edited: Matt J on 22 Jan 2024
You could (see my other answer), but I'm pretty sure that's what the adjacency() command is already doing internally.

Sign in to comment.

More Answers (1)

Matt J
Matt J on 22 Jan 2024
Edited: Matt J on 22 Jan 2024
edges = [1 2; 2 3; 3 1; 2 4; 4 5; 4 1];
data=[0.276
0.679
0.655
0.162
0.118
0.333];
m=max(edges(:));
A=accumarray(edges,data,[m,m],[],0,1);
out=sum(A+A.',2) %assume it's a non-directed graph
out =
(1,1) 1.2640 (2,1) 1.1170 (3,1) 1.3340 (4,1) 0.6130 (5,1) 0.1180

Categories

Find more on Data Distribution Plots in Help Center and File Exchange

Products


Release

R2021b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!