How to alter data (multiply) from all the columns of multiple text files in a folder

I have multiple text files locate in a folder.The names of the text files varies.How shall call them & multiply all the values inside all the text files with 10^-6 in a loop.

Attached 3 text files for refernces.I've made a small code but its ineffective as file name changes and not a value of numstr.

filenames = 'Path1_Step_0001';
for i = 1:length(filenames)
s{i} = readmatrix (['Path1_Step_' numstr(i).'txt']);
end

Answer 1

[Mathieu NOE]

hello

this is my suggestion ... the natural sorting order of the files may not be critical here, but it may be helpful another day , so this is a bonus ... natsortfiles is available from the FEX : Natural-Order Filename Sort - File Exchange - MATLAB Central (mathworks.com)

I found to save the data that importdata is a bit faster than readmatrix , I leave it to you to choose the best option;

clc
clearvars
% reading  of data txt files 

Folder = cd;
FileList  = dir (fullfile(Folder, 'Path1_Step_*.txt'));

FileList_sorted = natsortfiles({FileList.name}); % sort file names into order
M = numel (FileList_sorted);


for iFile = 1:numel(FileList)
    FileName = FileList_sorted{iFile};
    FileNamePath = fullfile(Folder, FileName);
    
    % load the data : choose one or the other option
    tic
    data{iFile} = importdata(FileNamePath); % faster
    toc 
    tic
    s{iFile} = readmatrix (FileNamePath); % slower
    toc
end

[Ramesh Bala]

Perfect Mathieu ,

Thanks ,it indeed worked well.

[Mathieu NOE]

My pleasure !

[Ramesh Bala]

One more kind question here :

I have altered the cell array with power multiply

s{iFile} = readmatrix (FileNamePath,'NumHeaderLines',4)*10^-6

Is it possible to save the altered cell array now as the same file names texts (like previously Path1_Step_0001 so on ?

I tried to convert it to matrix ? ,whether dlmwrite works in this case ?

fin = cell2mat(s{iFile}); %cell to matrix

dlmwrite (fin,'delimiter','\t','precision',3);

[Mathieu NOE]

this would be my suggestion ...

are you sure that all columns in the file must be multiplied by 10^-6 ?

the output data is saved with a different name (with _out.txt)

clc
clearvars
% reading  of data txt files 

Folder = cd;
FileList  = dir (fullfile(Folder, 'Path1_Step_*.txt'));

FileList_sorted = natsortfiles({FileList.name}); % sort file names into order
M = numel (FileList_sorted);


for iFile = 1:numel(FileList)
    FileName = FileList_sorted{iFile};
    FileNamePath = fullfile(Folder, FileName);
   
    % load the data : choose one or the other option
%     tic
%     data{iFile} = importdata(FileNamePath); % faster
%     toc 
    tic
    s{iFile} = readmatrix (FileNamePath); % slower
    toc
    
    % export data after applying a 10^-6 factor (applies on all columns ??)
    data_out = s{iFile}*10^-6;
    
    filename_out = [FileName(1:length(FileName)-4) '_out.txt'];
    writematrix(data_out, filename_out,"Delimiter","tab");
    
end

[Ramesh Bala]

Thanks again.

As of now yes for all the columns , in future if its specific column ( lets say column 1)

the below modified one works well right or do you have any other suggestion.

data_out = s{iFile}(:,1)*10^-6;

[Mathieu NOE]

you're welcome

your code will only save the corrected (first) column

if you want to keep all columns and define by a vector, which columns have to be changed , you can do that :

clc
clearvars
% reading  of data txt files 

Folder = cd;
FileList  = dir (fullfile(Folder, 'Path1_Step_*.txt'));

FileList_sorted = natsortfiles({FileList.name}); % sort file names into order
M = numel (FileList_sorted);


for iFile = 1:numel(FileList)
    FileName = FileList_sorted{iFile};
    FileNamePath = fullfile(Folder, FileName);
   
    % load the data : choose one or the other option
%     tic
%     data{iFile} = importdata(FileNamePath); % faster
%     toc 
    tic
    s{iFile} = readmatrix (FileNamePath); % slower
    toc
    
    % export data after applying a 10^-6 factor (applies on all columns ??)
    col = [1 5 6]; % define here which columns must be corrected (one or several)
    data_out = s{iFile}; % init the entire matrix 
    data_out(:,col) = data_out(:,col)*10^-6; % correct only defined columns
    
    filename_out = [FileName(1:length(FileName)-4) '_out.txt'];
    writematrix(data_out, filename_out,"Delimiter","tab");
    
end

[Ramesh Bala]

Thank you for all the suggestions.It's perfcetly working now.

[Mathieu NOE]

My pleasure

[Sideris Tzid]

hello I have pretty much the same task to finish. Problem is that the script will only multiply the text of the folder path and not the text in every subfolder and it will only multiply the data from the last text file.

clc

clearvars

Folder = 'C:\Users\sideris\Desktop\20101023_10324640';

FileList = dir (fullfile(Folder, '*.txt'));

FileList_sorted = natsortfiles({FileList.name}); % sort file names into order

M = numel (FileList_sorted);

for iFile = 1:numel(FileList)

FileName = FileList_sorted{iFile};

FileNamePath = fullfile(Folder,FileName);

tic

s{iFile} = readmatrix (FileNamePath);

toc

data_out = s{iFile}*0.0001;

filename_out = [FileName(1:length(FileName)-4) '_out.txt'];

writematrix(data_out, filename_out,"Delimiter","tab");

end

for example from this folder, it will only multiply the values of KRK1_5S00Z2.txt

I am in great pain, since the guy that is responsible for me at my intership is like "oh the data is in μm/s^2 , make them cm/s^2. It is seismic data btw

[Mathieu NOE]

hello

I am not 100% sure to understand your issue

can you share some of the data files and explain again what the results should be ?

[Sideris Tzid]

I'm sorry for my english.

Ummm actually I fixed the "last text" issue.

The problem that remains is that I have a folder which looks like this

each one of the subfolders has its own subfolders and so on.

The script that I'm running at the moment is :

clc

clearvars

Folder = 'C:\Users\sideris\Desktop\folder example';

FileList = dir (fullfile(Folder, '*.txt'));

FileList_sorted = natsortfiles({FileList.name}); % sort file names into order

M = numel (FileList_sorted);

for iFile = 1:M

FileName = FileList_sorted{iFile};

FileNamePath = fullfile(Folder,FileName);

tic

s{iFile} = readmatrix (FileNamePath);

toc

data_out = s{iFile}*0.0001;

filename_out = Folder+"\"+[FileName(1:length(FileName)-4) '_out.txt'];

writematrix(data_out, filename_out,"Delimiter","tab");

end

That script only works if all my text files are in the same folder. Is there any way to make that script read all the txt files from every subfolder?

[Mathieu NOE]

hello

look there and see code provided by ImageAnalyst

How do I read Folders with subfolders ? - MATLAB Answers - MATLAB Central (mathworks.com)