# Find the coordinates of the nodes of an matrix inside another matrix

3 views (last 30 days)
Alberto Acri on 20 May 2024
Answered: Matt J on 21 May 2024
I would like to find the coordinates of the nodes of an matrix 'nodes_portion' inside a larger matrix 'nodes_e'. (In this case all 'nodes_portion' is contained in 'nodes_e').
What I want to get are the rows where the nodes of 'nodes_portion' are inside 'nodes_e'.
I am using a for loop however it takes much longer than expected. Any way to optimize the search?
nodes_file = importdata("nodes.mat");
nodes_e = nodes_file.nodes_e;
nodes_portion = nodes_file.nodes_portion;
row_t = {};
for j = 1:5 %:height(nodes_portion)
row = {};
for k = 1:height(nodes_e)
[r,~] = find(nodes_e(k,1) == nodes_portion(j,1) & nodes_e(k,2) == nodes_portion(j,2) & nodes_e(k,3) == nodes_portion(j,3));
row = [row;{r}];
end
row_t = [row_t;{row}];
end
% ==========
rr = {};
for s = 1:height(row_t)
[r,c] = find(cellfun(@(x) isequal(x,1), row_t{s,1}(:,1)));
rr = [rr;{r}];
end

Matt J on 21 May 2024
Sounds like you could just use ismember(___,'rows')

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