How do I store result from a loop into matrix?

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Syed Farez 2018-5-6

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评论： Syed Farez 2018-5-6

采纳的回答： Wick

I have 360 signals to be processed and I'm using STFT for my project. The result for one signal returns:

S = 33x147 double

How do I take only the first column from every 360 signals processed and store it in the same matrix? And how do I make a loop to make it do the same thing but advance to the next column up to the 147th column until I've 147 different matrices of result S?

Thank you in advance.

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Ameer Hamza 2018-5-6

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Does your result require 147 matrices at the end? Like this

Result{1} = [first columns of S for all 360 signals] = 33 x 360 matrix
Result{2} = [second columns of S for all 360 signals] = 33 x 360 matrix
....
Result{147} = [147th columns of S for all 360 signals] = 33 x 360 matrix

Syed Farez 2018-5-6

编辑：Syed Farez 2018-5-6

Yes Ameer, exactly like that brother. Sorry for the misguided question. I've corrected it.

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Wick 2018-5-6

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编辑：Wick 2018-5-6

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The first column of S can be indexed S(:,1). The nth is S(:,n);

Instead of making 360 different matrices with different names, we're going to make a three-dimensional array, A, with 360 different pages.

      clearvars
      num_rows = 33;
      num_signals = 360;
      num_pages = 147;
      A = zeros(num_results, num_signals, num_pages);
    for jj = 1:num_signals
        % replace the following line with your calculation of S
        S = rand(num_results,num_pages);
        A(:,jj,:) = reshape(S,num_results,1,num_pages);
    end

Each page of A (the different columns from your values of S pasted together into a matrix) can be indexed as:

page_of_columns = A(:,:,n)

where 'n' is the column id you want (from 1 to 147 in your example)

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Wick 2018-5-6

编辑：Wick 2018-5-6

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    clearvars
    num_rows = 33;
    num_signals = 360;
    num_pages = 147;
    num_results = 1;
    A = zeros(num_results, num_signals, num_pages);
    % load a .mat file
    load ('Defect_Signals_with_Labels.mat');
    for jj = 1:num_signals
           x = Signals_Combined(:,jj);
           .....
           S = 20*log10(S + 1e-6);
           A(:,jj,:) = reshape(S,num_results,1,num_pages);
    end

The assumption is that 'S' is different each time based on whatever is above it inside the loop.

Syed Farez 2018-5-6

Okay. I think I've got it now and it worked like a charm. Just needed a bit troubleshooting. Thank you very much for your help!! You certainly saved me today Sir. :')

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