I have sensors values in the form of multiple csv's want to read each file and if the length is less than 800 take average of each column and insert in the last of csv

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shery khan 2022-6-25

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https://ww2.mathworks.cn/matlabcentral/answers/1748105-i-have-sensors-values-in-the-form-of-multiple-csv-s-want-to-read-each-file-and-if-the-length-is-less

评论： shery khan 2022-6-26

following is the code i am testing on single file where as i have multiple files that have missing values i want to know how can i check the length of file and ignore first column and if length is less then 800 row get the length first and take average of each column and add average at the end of file . suppose a file have 631 rows . so i need to fill left rows by average means 169 values are filled .

1st Row 2nd 3rd 4th

--

631Row

average value

--

800 Rows

i have files that contain 4 columns but i am working on 3 columns first column is ignored

Kindly help me in this regard ..

tmp=load('D:\Testing\1464882962.m_proc_gyro.csv');
if(length(tmp)~=800)
    for i=1:length(tmp)
            Imp_three=tmp(:,2:end);
            First_col=Imp_three(:,1);
            Second_col=Imp_three(:,2);
            Third_col=Imp_three(:,3);
            M1=mean(First_col);
            M2=mean(Second_col);
            M3=mean(Third_col);
            
            s1 = size(First_col,1); % Rows
            s2 = size(Second_col,2);
            s3 = size(Third_col,3);
            
            
            MArray=[M1,M2,M3];
        
    end        
            
end        

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Answer 1

Voss 2022-6-25

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编辑：Voss 2022-6-25

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This will do that, including the first column (which you can continue to ignore):

tmp=load('D:\Testing\1464882962.m_proc_gyro.csv');
n_rows_target = 800; % extend to 800 rows, with mean of each column
n_rows = size(tmp,1);
if n_rows < n_rows_target
    mean_tmp = mean(tmp,1);
    tmp(n_rows+1:n_rows_target,:) = repmat(mean_tmp,n_rows_target-n_rows,1);
end

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Voss 2022-6-25

编辑：Voss 2022-6-25

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Consider the fact that including new data that is the average of the existing data doesn't change the average of the overall data:

x = 1:9
x = 1×9
     1     2     3     4     5     6     7     8     9
mx = mean(x)
mx = 5
x(end+1) = mx
x = 1×10
     1     2     3     4     5     6     7     8     9     5
mx = mean(x)
mx = 5
x(end+1) = mx
x = 1×11
     1     2     3     4     5     6     7     8     9     5     5
mx = mean(x)
mx = 5
x(end+1:end+100) = mx
x = 1×111
     1     2     3     4     5     6     7     8     9     5     5     5     5     5     5     5     5     5     5     5     5     5     5     5     5     5     5     5     5     5
mx = mean(x)
mx = 5

The average is going to stay at 5 no matter how many 5's you append to the end of it.

Therefore, the method in my answer is equivalent to your method.

If you disagree or aren't sure about that, I ask you again to please show me what the result should be in this case:

tmp = reshape(1:28,[],4)
tmp = 7×4
     1     8    15    22
     2     9    16    23
     3    10    17    24
     4    11    18    25
     5    12    19    26
     6    13    20    27
     7    14    21    28
n_rows_target = 10; % extend to 10 rows, with mean of each column
n_rows = size(tmp,1);
if n_rows < n_rows_target
    mean_tmp = mean(tmp,1);
    tmp(n_rows+1:n_rows_target,:) = repmat(mean_tmp,n_rows_target-n_rows,1);
end
disp(tmp);
     1     8    15    22
     2     9    16    23
     3    10    17    24
     4    11    18    25
     5    12    19    26
     6    13    20    27
     7    14    21    28
     4    11    18    25
     4    11    18    25
     4    11    18    25

That is, how would those last 3 rows be different using your method?

mean(tmp(1:7,:),1)
ans = 1×4
     4    11    18    25
mean(tmp(1:8,:),1)
ans = 1×4
     4    11    18    25
mean(tmp(1:9,:),1)
ans = 1×4
     4    11    18    25
mean(tmp(1:10,:),1)
ans = 1×4
     4    11    18    25

Image Analyst 2022-6-25

在 MATLAB Online 中打开

This answer works for one specific file. You said "i have multiple files" so to solve that part, make sure to check my answer below where I direct you to the FAQ.

Since I didn't see looping over multiple files in your code, I think maybe you couldn't figure out how to adapt it, so I'll do it for you below.

% Specify the folder where the files live.
myFolder = 'D:\Testing';
% Check to make sure that folder actually exists.  Warn user if it doesn't.
if ~isfolder(myFolder)
    errorMessage = sprintf('Error: The following folder does not exist:\n%s\nPlease specify a new folder.', myFolder);
    uiwait(warndlg(errorMessage));
    myFolder = uigetdir(); % Ask for a new one.
    if myFolder == 0
        % User clicked Cancel
        return;
    end
end
% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.csv'); % Change to whatever pattern you need.
theFiles = dir(filePattern);
% Loop over all CSV files in the folder.
for k = 1 : length(theFiles)
    baseFileName = theFiles(k).name;
    fullFileName = fullfile(theFiles(k).folder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    % Now read it in as an array with readmatrix()
    thisMatrix = readmatrix(fullFileName);
    % Now process thisMatrix as you have been doing.
end