array to vector conversion

I have a 3-dimensional array A which has 450 rows,210 coulms, 4 layers. I want to make a regression between A(450,210,1) and A(450,210,3), A(450,210,2) and A(450,210,4). For that I need to convert the array to 4 vecotrs. I don't know how to do that. I tried Reshape function but couldn't get what I want. Any help is appericiated.

Answer 1

[Oleg Komarov]

A  = rand(450,210,4);

EDIT

% Switch 2nd dim with 1st
A = permute(A,[2,1,3]);
% Reshape into vector each layer
A = reshape(A,450*210,4)

Each column now is the vectorized layer.

[Hassan]

thanks a lot for the help. I think I need to do a step before using that since now it's writing the first column and then 2nd column, ... but I need first rwo,2nd row,...

A = rand(450,210,4);

A=tranpose(A(:,:,1))

A1 = reshape(A(:,:,1),450*210,1)

[James Tursa]

You can use the MTIMESX FEX submission to do an nD transpose on your original A array. That will turn your rows into columns and get them next to each other in memory. Then you can do the rest of the calculation as shown above. e.g.,

A = mtimesx(1,A,'T'); % Transpose the first two dims

You can find MTIMESX here:

http://www.mathworks.com/matlabcentral/fileexchange/25977-mtimesx-fast-matrix-multiply-with-multi-dimensional-support

[Hassan]

thanks for the help. I couldn't run the code. it gives me an error which says A C/C++ compiler has not been selected with mex

-setup. I don't know what should I do to fix it.

[Hassan]

thanks Oleg for refining the code.

[James Tursa]

Type the following at the MATLAB command line prompt:

mex -setup

Then press Enter

Then enter the number of a C compiler such as lcc

Then press Enter again

Then try running mtimesx again.

[Hassan]

thanks James, it's working now.