CODEWITHSUNDEEP
matlabmatrix
Luis Enriquez
Luis Enriquez

Reputation: 55

Matlab - Create a bigger matrix out of a smaller one with blank spaces

Let's say I have a 3 x 3 matrix (A), and I want to make it a 5 x 5 matrix (B), but the Matrix A has the following content:

1 2 3
4 5 6
7 8 9

And the resulting bigger matrix B, needs to have the following content:

1 0 2 0 3
0 0 0 0 0
4 0 5 0 6
0 0 0 0 0
7 0 8 0 9

I know this can be done with some "Fors" following a sequence like:

  %% We get the dimensions of our matrix. 
  [xLength, yLength] = size(InMat); 

  %% We create a matrix of the double size.
  NewInMat = zeros(xLength * 2, yLength * 2);

  %% We prepare the counters to fill the new matrix.
  XLenN = (xLength * 2) -1;
  YLenN = (yLength * 2) - 1;

  for i = 1 : XLenN
      for j = 1 : YLenN
         if mod(i, 2) ~= 0
           if mod(j, 2) ~= 0
              NewInMat(i, j) = InMat(i, j);
           else
              NewInMat(i,j) = mean([InMat(i, j - 1), InMat(i, j + 2)]);  
           end
         end
    end
end

But I would like to know if there is an easier way, or if Matlab has a tool for doing this task. Many thanks in advance!

Upvotes: 1

Views: 32

Answers (1)

rahnema1
rahnema1

Reputation: 15837

You can use indexing:

InMat = [...
1 2 3
4 5 6
7 8 9];
s = size(InMat)*2-1;
NewInMat(1:2:s(1), 1:2:s(2)) = InMat;

Here NewInMat is allocated and filled at the same time.

Upvotes: 5

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