MATLAB: Singleton dimention as last dimension in matrix

singleton dimension

Hello,

How do I create a singleton dimension as a last dimension in matlab, for example, so that size = 64 64 1.

I've tried reshape(x,[64 64 1]), but the resultant matrix is 64×64, not 64x64x1. Similarly with permute.

Thanks for any help!

Best Answer

Arrays in MATLAB have an implied infinitely long series of trailing singleton dimensions. You can index into them with no problem. For example

>> x = rand(3,3);
>> x(2,3,1,1,1,1,1,1,1,1,1,1,1)

is a valid indexing into x.

What is it that you are trying to do, that you need to emphasize that the array is 64x64x1?

Related Solutions

MATLAB: How can i reshape a 20370×1 matrix into 2037x10x1

MATLAB treats ALL matrices as having essentially an infinite number of trailing singleton dimensions. So a 2x3 matrix is really 2x3x1x1x1x1x1x1... Those trailing singleton dimensions are not reported by size or whos however.

X = zeros(2,3,1,1);
whos X
  Name      Size            Bytes  Class     Attributes
    X         2x3                48  double              
size(X)
ans =
     2     3

However, MATLAB indeed knows that X has trailing singleton dimensions. You can convince yourself of that easily enough.

size(X,3)
ans =
     1
size(X,12)
ans =
     1

Your 2037x10 matrix is indeed a 2037x10x1 matrix. So a simple reshape was all you needed to do.

B = reshape(A,[2037,10]);

MATLAB: How to sum over specific dimensions in a n-dimensional array

Join the trailing dimensions at first:

x = rand(2,3,4,5,6);
d = 3;
n = ndims(x);
s = num2cell(size(x));
y = reshape(x, s{1:n-d}, []);
result = sum(y, n-d+1)

Best Answer

Related Solutions

MATLAB: How can i reshape a 20370×1 matrix into 2037x10x1

MATLAB: How to sum over specific dimensions in a n-dimensional array

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