MATLAB: How to change every value not equal to X in every rows

change rowsloopmatrix manipulation

Hi,

I have a matrix (20000×365) and I have a vector(20000×1) in which I have the column assiciate with the number that I DON'T want to change (This number change for every rows) .

For every rows I want to change every colums, beside the one that is in the vector, for 0

EX: matrix [18 3 1 11; 8 10 11 3; 9 14 6 1; 4 3 15 21]

Vector [3,1,3,2]

The answers should be [0 0 1 0; 8 0 0 0; 0 0 6 0; 0 3 0 0]

Thanks for your help!

Best Answer

Wanted = zeros(size(matrix));
indices=sub2ind(size(matrix),1:size(matrix,1),Vector);
Wanted(indices)=matrix(indices)

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MATLAB: How to insert columns into an existing matrix without deleting existing columns

Try this:

matrix = rand(10,8);
index_excl = [0   0   1   0   0   0   0   1   0   0   1] > 0;
AddCols = nnz(index_excl);
new_matrix = zeros(size(matrix,1), size(matrix,2)+AddCols);
new_matrix(:, ~index_excl) = matrix;

The code creates ‘new_matrix’ as a zeros array of the desired size, then writes the columns of the original ‘matrix’ array to the ones you want to add.

MATLAB: How do i get the values of a 2D matrix based on column indices

 Output = matrix(sub2ind(size(matrix), 1 : size(matrix, 1), column_indices))

Best Answer

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MATLAB: How to insert columns into an existing matrix without deleting existing columns

MATLAB: How do i get the values of a 2D matrix based on column indices

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