Dynamically read all files in a file process them and combine the processed data in one matrix

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Dexter 2021-11-24

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https://ww2.mathworks.cn/matlabcentral/answers/1595329-dynamically-read-all-files-in-a-file-process-them-and-combine-the-processed-data-in-one-matrix

评论： Dexter 2021-11-25

Hi, I have a folder with various datasets, I want to read all the datasets and process them. Each datasets have 4 columns (A, B, C , D),

each column represent a signal that I want to process, in this case to filter and calculate the rms value of the signal. The final result should be a table with columns A,B,C,D and row(i) should have the rms values of the signas(i), i.e the rms values of the first dataset . My main problem is that when using reshape, in the second iteration, I am getting:

Error using reshape

Number of elements must not change. Use [] as one of the size inputs to automatically calculate the appropriate size for that dimension.

files = dir('*.csv');
num_files = length(files);
results = cell(length(files), 1);
for i = 1:num_files
  results{i} = readmatrix(files(i).name);
end
% 
% results{2}
features = []
results_k = results{1}
for i = 1:num_files
   results_k = results{i}
   len = length(results_k)
   results_k = results_k(~isnan(results_k))';
   %len = len/4
   results_k = reshape(results_k,len,4)
   firstCol = results_k(:,1)
   secondCol = results_k(:,2)
   thirdCol = results_k(:,3)
   fourthCol = results_k(:,4)
   bpFilt = designfilt('bandpassiir','FilterOrder',4, ...
         'HalfPowerFrequency1',0.08,'HalfPowerFrequency2',1, ...
         'SampleRate',20,'DesignMethod','butter');
   firstCol = filtfilt(bpFilt,firstCol);
   secondCol = filtfilt(bpFilt,secondCol);
   thirdCol = filtfilt(bpFilt,thirdCol);
   fourthCol = filtfilt(bpFilt,fourthCol);
   rms1 = rms(firstCol)
   rms2 = rms(secondCol)
   rms3 = rms(thirdCol)
   rms4 = rms(fourthCol)
   new_features=[rms1,rms2,rms3,rms4]
   features = [features new_features]
end