How can I add an extra dimension to make the array 2D to 3D?

clear all;
for idx = 1:258 
    name = '';
        if idx < 10
            name = strcat('0',int2str(idx),'.mat');
            load(name);
        else
            name = strcat(int2str(idx),'.mat');
            load(name);
        end

data=sqrt(sum([abs(raw_data)].^2,3));

%data = (data,idx)
save("01_new.mat", "data")
end

There are 258 mat files( named as "01.mat" to "258.mat") in the folder. So I am running the loop upto 258. All the mat files contain different image, but has the same data structure 320*320*16.

Then I removed one dimension using sum of square.

Now, I am trying to add 3rd dimension in the "data" see the commented line. The third dimension will contain the mat file number from the folder.

Then finally I want to stack all the 258 files into one ".mat" file.

Answer 1

[Jan]

Reduce the clutter:

name = '';
if idx < 10
    name = strcat('0',int2str(idx),'.mat');
    load(name);
else
    name = strcat(int2str(idx),'.mat');
    load(name);
end

Smarter:

name = sprintf('%0d.mat', idx);

This fills in a leading zeros on demand.

Do no load data directly into the workspace, because this can cause unexpected side-effects. Catch the output of load() in a variable instead.

[] is Matlab's operator for the concatenation of arrays. In [abs(raw_data)] you concatenate the output of the abs() command with nothing. Simply omit the square brackets.

clear all removes all loaded functions from the memory. Reloading them from the slow disk wastes a lot of time. There are no further benefits of this command, so simply omit it.

It is safer to specify files with a full path. Relying on the current folder is fragile, e.g. when a callback of a GUI or timer changes the current folder. This is so hard to debugm, that it is a good programming practice to use full paths in general.

Summary:

Folder = cd;   % Or better define the folder explicitly
Result = zeros(320, 320, 258);
for idx = 1:258
    File = fullfile(Folder, sprintf('%0d.mat', idx));
    Data = load(File);
    Result(:, :, idx) = sqrt(sum(Data.raw_data .^ 2, 3));
end
save(fullfile(Folder, '01_new.mat'), 'Result');

Are the value of the raw_data real? Then there is no need for the abs() command, because the elementwise squaring .^2 removes the sign also.

[Gulfam Saju]

Error using save
Cannot create 'Result.mat' because '01_new.mat' does not exist.

Error in data_convert (line 9)
save(fullfile(Folder, '01_new.mat', 'Result');
 

I got this error

[Gulfam Saju]

Thanks it worked

[Gulfam Saju]

Can you please suggest, How can I do that for a single file?

[Jan]

How can you do what for a single file?