How do I repeat a function on each and every column of a 241X1236 array?

I am able to do it for one column

cwt1 = cwt(All_mean(:,1), 1:64, 'sym8');

Here, All_mean is the 241X1236 array. cwt, 1:64 and 'sym8' is the function.

I have something like this

    for 
        z= 1: size(All_mean, 2)
        cwt1 = cwt(All_mean(:,1), 1:64, 'sym8');
        cwt(z)=cwt(All_mean(:,z), 1:64, 'sym8'); 
    end
The output I get is a 64X241 array. I need to store every output array with a name like 'cwt1', 'cwt2', 'cwt3'.... 'cwt1236'.

Please can anyone help me? I am very new to matlab.

Answer 1

[Star Strider]

I would save them in a cell array:

cwtc = cell(size(All_mean,2),1);                                       % Preallocate Cell Array
for k1 = 1:size(All_mean,2)
    cwtc{k1} = cwt(All_mean(:,k1), 1:64, 'sym8');
end

Now, cwt of each column is in its own cell as a (64x241) double array. Column 1 is in ctwc{1}, and so for the rest.

[Dee]

Thank you so much! It worked beautifully. And thanks for the explanation too- I didn't realize that I had to pre-allocate.

[Star Strider]

As always, my pleasure! Thank you!

Preallocation allows MATLAB to put each element of an array created in a for loop in an existing segment of memory, rather than having to allocate a new segment for it, and in some situations, re-writing the entire array in contiguous segments in each iteration. Preallocation isn’t absolutely necessary (code will work without it), although with it, code is significantly faster and more efficient.

[Dee]

I see. This is very valuable information for a new programmer like me. Thanks again!

[Star Strider]

As always, my pleasure!

Answer 2

[Ameer Hamza]

Why would you want to do that? Managing values in form of matrices is much easier, efficient and robust as compared to naming your variables like 'cwt1', 'cwt2', ... . cwt1 is same as cwt(:,1), so use the better option. Naming the variables like that is unrecommended: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval. As you mentioned, you are new to MATLAB, this is good chance for you to start following recommended coding practices to make your code efficient and less buggy.

[Dee]

Thanks for your suggestion.