MATLAB: Finding coordinates or locations in matrix

findmatrixsubs

Hi, I am trying to find a way of extracting the coordinates of the values that are larger than 20 in a magic(5) matrix.

I would like to have the coordinates specified as 3,5 instead of 15 and so on,, is that possible?

Thanks

>> r=magic(5)

r =

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

>> b=r>20

b =

     0     1     0     0     0
     1     0     0     0     0
     0     0     0     0     1
     0     0     0     1     0
     0     0     1     0     0

>> find(b==1)

ans =

Best Answer

[row,col] = find(...)

Related Solutions

MATLAB: Find row with certain value and put in cell

result = arrayfun(@(k) unique(B(A(:,k)==1,:)).', 1:size(A,2), 'un', 0)

MATLAB: How to stop incidence function rearranging the edges of a graph

The reordering isn't happening when the incidence of the graph is computed, but instead at the moment that the graph is constructed: The graph and digraph classes always standardize the order of the edges, the original order isn't preserved in the object.

If you just need the incidence matrix based on s and t, and using original ordering, you can compute this directly:

nn = max([s(:); t(:)]); % number of nodes
ne = length(s); % number of edges
inc = sparse([s(:) t(:)], (1:ne)'*[1 1], ones(ne,1)*[-1 1], nn, ne);

If you need the graph itself, too, you can make the original order of the edges to be stored as the Weight variable in the graph's Edges table.

g = graph(s, t, 1:length(s)); % Verify that g.Edges.Weight contains the original placement of each edge in the (s, t) inputs
inc2 = incidence(g);
inc2(:, g.Edges.Weight) = inc2;
isequal(inc, inc2)

Best Answer

Related Solutions

MATLAB: Find row with certain value and put in cell

MATLAB: How to stop incidence function rearranging the edges of a graph

Related Question