converting multiple file of 4D to 3D files

i have 80 files of 4D double (140x122x180x#)

i need the files in 3D (140x122x180)

i have tried these solutions but does not come out as expected

files = B % 140x122x180x#
threeD = permute(files[1,2,3,4])
% the result will be 4D double 

% i also tried 
threeD = squeeze(num2cell(permute(files,[1,2,3,4]),1:3))
% the result will be #x1 cells

current coding :

cd ('path'); 

files=dir('*.mat');          % find all |.mat| files in the current directory.
totalfile = numel(files);    % count those files.
C = cell(1,totalfile);       % preallocate a cell array for the loaded data.
                            
for a = 1:totalfile          % loop over the number of files.
    T = load(files(a).name)  % load the data from each file 
    C(a) = struct2cell(T);   % convert structure to cell, allocate to cell array.
    
    M = cat(4,C{:})          % concatenate all MxN matrices into MxNxP array, 
                             % 3 dimensional concatenate
    
% ???
    save(['path/zscore_' num2str(a) '.mat'],'M');
end 

thank you

[Rik]

What about this?

B=rand(140,122,180,3);
A=B(:,:,:,2);

[Hanisah noh]

thank you!

the result is 140x122x180 using

A = B(:,:,:,2);

may i know

what does it indicate ?and

the value 2 is for ?

[Rik]

I don't know what your variables mean, they're your variables.

The 2 is just an example, as you didn't secribe what value # should have. You wanted a length of 1 in the fourth dimension, that is what this code does. It selects the second book. (in general the first 2 dimensions of an array are called rows and columns, the third is often called page, and some people call the fourth dimension book (i.e. a collection of pages))

[Hanisah noh]

i see. thanks ! big help

Answer 1

[Vinai Datta Thatiparthi]

Hey Hanisah,

As mentioned by @Rik, iterate through the collection of 4D matrices to get your 3D values.

For example,

for i = 1:size(B, 4)
    A = B(:,:,:,i) % Simple example to slice your 4D matrices
end

Hope this helps!

[Hanisah noh]

thank you. this helps 👍