Using accumarray to sum all values associated with a given node

Question

L'O.G. 2024-1-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2072871-using-accumarray-to-sum-all-values-associated-with-a-given-node

编辑： Matt J 2024-1-22

采纳的回答： Matt J

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);

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Answer 1

Matt J 2024-1-22

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https://ww2.mathworks.cn/matlabcentral/answers/2072871-using-accumarray-to-sum-all-values-associated-with-a-given-node#answer_1394716

编辑：Matt J 2024-1-22

在 MATLAB Online 中打开

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

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L'O.G. 2024-1-22

Ah ok, I was just wondering if I could've used accumarray after all. Thank you!

Matt J 2024-1-22

编辑：Matt J 2024-1-22

You could (see my other answer), but I'm pretty sure that's what the adjacency() command is already doing internally.

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Answer 2

Matt J 2024-1-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2072871-using-accumarray-to-sum-all-values-associated-with-a-given-node#answer_1394721

编辑：Matt J 2024-1-22

在 MATLAB Online 中打开

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