How can i use Discrete wavelet transform (DWT) on a matrix

Question

Sameer Ingale 2023-2-3

0
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https://ww2.mathworks.cn/matlabcentral/answers/1906120-how-can-i-use-discrete-wavelet-transform-dwt-on-a-matrix

回答： Nayan 2023-4-11

I have data set of 327 subjects i have read all the dataset in one variable that is T1. T1 size is 1 x 327 and each cell has 19200 x 14. i want to read each data and perform dwt on each one data i.e 19200x 1 and i want it in a loop ( like 1 to 14). I want 2 - level dwt and db4 and extract detail and approximation in matrix

Can someone please help me i have done several methods but didn't get the answer

%% READING THE DATA 
% Task1
myFolder = 'D:\Finall Sorted data\Task 1';
% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.csv');
theFiles = dir(filePattern);
n = length(theFiles);
for k = 1 : n
    baseFileName = theFiles(k).name;
    T1{k} = readmatrix(fullfile(theFiles(k).folder, baseFileName));  
end 
S = []; 
P = 0; 
sz = 0; % Size of matrix
for i = 1 : 327 
    
    S{i} = T1{1,i}; % to read the data
    
    for j = 1 : 14
        
        P = S(1:19200:j);
        sz = size(P); 
        % dwt method       
    end
end

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Sameer Ingale 2023-2-4

编辑：Sameer Ingale 2023-2-4

I want the size of data within S.

so what should i use to instead of cell array to process ?

Walter Roberson 2023-2-4

在 MATLAB Online 中打开

    for j = 1 : 14
        
        P = S(1:19200:j);

Suppose j were 1. Then you would have S(1:19200:1) . But the end value is the same as the initial value, so that will be just S(1) . The same is true for all the other values of j from 1 to 14. j would have to be at lest 19201 for 1:19200:j to include more than one element.

Where you for some reason interested in 1:j:19200 ? That is, the first time [1, 2, 3, 4, ...] and the second time [1, 3, 5, 7, ...] and the third time [1 4 7 10, ...] and so on? Or were you interested in S(1:19200,j) ?

size(1:19200,j) is going to be 19200 x 1 unless j is non-scalar (or is the logical value false)

If you want to know about the size of the data in T1 then you would be more likely to use

S = T1{1,i};

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