MATLAB: How to convert 1D element into 2D element in a matirx

2drow-column index

hi, i need to find the location of elements in a matrix as (row,column) value. what function is used to get the row and column of a element?

Best Answer

Use find function

 doc find

Example

A=[1 2 3;4 5 6;7 8 9]
[ii,jj]=find(A)

Related Solutions

MATLAB: How to find the location of element in matrix

I=[2 3 10 4 6; 1 4 7 5 3; 5 2 8 4 3;8 2 1 7 3;1 9 8 3 4;];
D = padarray(I,[1 1],0,'both');
s = size(I);
N = padarray(reshape(1:numel(I),s),[1 1],0,'both');
pt = [1 1 1;1 0 1;1 1 1] > 0;
s1 = s+2;
out = zeros(s);
for ii=2:s1(1)-1
    for jj=2:s1(2)-1
        D1 = D(ii-1:ii+1,jj-1:jj+1);
  K = N(ii-1:ii+1,jj-1:jj+1);
  K = K(pt);
        [~,i0] = max(D1(pt));
  out(ii-1,jj-1) = K(i0);
    end
end

I=[2 3 10 4 6; 1 4 7 5 3; 5 2 8 4 3;8 2 1 7 3;1 9 8 3 4;];
D = padarray(I,[1 1],0,'both');
s = size(I);
pt = [1 1 1;1 0 1;1 1 1] > 0;
a = -1:1;
j1 = [1;1;1]*a;
i1 = j1';
i1 = i1(pt);
j1 = j1(pt);
s1 = s+2;
R = zeros(s);
C = zeros(s);
for ii=2:s1(1)-1
    for jj=2:s1(2)-1
        D1 = D(ii-1:ii+1,jj-1:jj+1);
        [~,i0] = max(D1(pt));
        R(ii-1,jj-1) = ii + i1(i0) - 1;
        C(ii-1,jj-1) = jj + j1(i0) - 1;
    end
end

I=[2 3 10 4 6; 1 4 7 5 3; 5 2 8 4 3;8 2 1 7 3;1 9 8 3 4;];
Ip = padarray(I,[1 1],0,'both');
s = size(Ip);
s0 = s - 2;
idxi = padarray(reshape(1:numel(I),s0),[1 1],0,'both');
ptr = reshape(bsxfun(@plus,(0:2)',(0:2)*s(1)),1,[]);
p2 = bsxfun(@plus,(1:s0(1))',(0:s0(2)-1)*s(1));
idx = bsxfun(@plus,p2(:),ptr([1:4,6:end]));
[~,ii] = max(Ip(idx),[],2);
s1 = size(idx);
out = reshape(idxi(idx(sub2ind(s1,(1:s1(1))',ii))),s0);
[R,C] = ind2sub(size(out),out);

MATLAB: Findout the second largest element in each row and its location in a matrix

One possible way is to find the largest values, replace them with a very small value (-Inf) and search for the new largest values:

A=[1 2 3 4 5; 6 7 9 8 10; 11 12 14 13 15] %your example A was a single row
m = max(A, [], 2); %find the max in each row
A(bsxfun(@eq, A, m)) = -Inf; %replace the max(s) by -Inf
m = max(A, [], 2)  %find the new max which is the second largest.

Best Answer

Related Solutions

MATLAB: How to find the location of element in matrix

MATLAB: Findout the second largest element in each row and its location in a matrix

Related Question