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POFinding all edges (and nodes) within X steps from a chosen line in an adjacency matrix in MATLAB
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  1. POFinding all edges (and nodes) within X steps from a chosen line in an adjacency matrix in MATLAB
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    copied!<p>I have a nx2 matrix of to-from nodes for a large network structure. I have used this to create a sparse adjacency matrix which I can plot using BIOGRAPH. My systems varies in size, the largest ones having more than 3000 nodes (obviously not suitable for plotting).</p> <p>If I choose a line, I want to be able to create a list of all lines and nodes that are within X "steps" from the original line (two nodes), for a given X (typically 3). It's clearly not too difficult using brute-force. However, I need to do this as quick as possible. </p> <pre><code> adj_mat = sparse(from_nodes, to_nodes, 1, s, s); </code></pre> <p>Is there a way I can to this using the adjacency matrix? Can I do it more efficiently using the to/from list?</p> <p>What I do now is finding the indices for the nodes connected to the chosen line, then search through the entire list of to-from nodes and finding all lines where either the to/from element is equal to one of the nodes of the chosen line. Then I use the new list of nodes and search through the entire to/from list, searching for these nodes again. </p> <p>The code I use now looks something like this:</p> <pre><code> % tempBranch = the branches connected to the list of the current branches k = 1; for i = 1:nnz(nodeList) % number of after step X-1 (for X=0 this is % equal to the nodes connected to the chosen line for j = 1:n % n = number of lines if branchList(j,1) == nodeList(i) || branchList(j,2) == nodeList(i) tempBranch(k) = j; k = k + 1; end end end </code></pre> <p>Thank you!</p>
 

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