MATLAB: What to use instead of horzcat for N-D Arrays

horzcatMATLABmultidimensional

Hello.

I have a 3D array (let's say 3 x 4 x 100, call it AA) and want to add zeros to the end of the long dimension (let's say to get it to 3 x 4 x 200, adding on BB that is also 3 x 4 x 100 with zeros). horzcat() isn't happy, and [AA BB] won't do it.

Suggestions? Thanks!

Doug Anderson

Best Answer

AA(end,end,200) = 0;

Related Solutions

MATLAB: N-D matrix accumarray

Yes, accumarray will do it easily. You just need to generate the correct subscripts for it, which is the cartesian product of all the indices in all the dimension, replacing the appropriate dimensions with your grouping variables:

A = randi(100, [3 4 2 7]);  %demo data
%generate indices in all the dimension, and replace appropriate one with grouping variables:
indices = arrayfun(@(s) 1:s, size(A), 'UniformOutput', false); %vector of indices in each dimension
indices{2} = [2 1 2 3];  %grouping in 2nd dimension
indices{4} = [3 3 2 1 3 2 4];  %grouping in 4th dimension
%calculate cartesian product of indices
[indices{:}] = ndgrid(indices{:});
indices = cell2mat(cellfun(@(v) v(:), indices, 'UniformOutput', false));
%apply accumarray with default sum function
B = accumarray(indices, A(:));

Edit: note that the above will work with arrays of any dimension (within reason, ndgrid will run out of memory for too many dimensions).

MATLAB: How to use ‘&’ between two different matrix

The dimensions of aa and bb are different. aa is 2X3 and bb is 3x2.. you have to transpose any of the matrix.

Eg:

cc = aa' & bb

cc = aa & bb'

Best Answer

Related Solutions

MATLAB: N-D matrix accumarray

MATLAB: How to use ‘&’ between two different matrix

Related Question