How to import a sequence of file .txt

Hello,

I am a recent matlab user who cannot understand how to import a large series of .txt files in sequence (each one is made up of a series of numbers).

I try to explain myself:

1) I should create a script that reads and imports in sequence and as vectors the .txt files contained in a certain folder (one file = one vector). The files are of the type

waveform_1_1.txt, waveform_1_2.txt up to _16_16 etc;

2) from time to time I should elaborate the vector with some function, "so as to obtain a certain number" to be associated with an element of a certain matrix. So the

elaboration of the waveform_1_1.txt I should associate it to the element 1,1, the elaboration of the waveform_1_2.txt I should associate it to the element 1,2 and so on.

Would anyone know how to do it?

Would anyone know how to help me complete the for loop in areas with "green % ......"

thank you

Marco

gdm = ones(16); % matrix that I have to fill

for i=1:256        % 256 is number of file.txt
    %..........
    %..........
    %..........
    Vector_mean_i = mean(%.......)    % now I have to average vector i 
    %..........
    %..........       %I have to insert the processing of the file, that is Vector_mean_i, in the first element of the gdm array and so on with the for loop
    %..........
end

Answer 1

[Mathieu NOE]

hello Marco

see below an example how to read all txt files inside a folder and do the batch processing - like here I simply do the averaging of the data and store it in an array

I don't know exactly how you wanted to use the first and second numrical indexes inside the data filename , but the code do extract them, see how you want to use that info

also note that this code does not follow the "natural" order of the filenames , so if that is important, we can use that very handy function natsortfiles available on File Exchange : Natural-Order Filename Sort - File Exchange - MATLAB Central (mathworks.com)

this is my demo code so far :

clc
clearvars
% reading  of data txt files 

% Folder = 'C:\Your\Folder';
Folder = cd;
FileList  = dir (fullfile(Folder, 'waveform_*.txt'));

for iFile = 1:numel(FileList)
    FileName = FileList(iFile).name;
    FileNamePath = fullfile(Folder, FileName);
    ind = findstr(FileName,'_');
    indp = findstr(FileName,'.txt');
    
    index1(iFile) = str2num(FileName(ind(1)+1:ind(2)-1)); % this is the first number in the filename 
    index2(iFile) = str2num(FileName(ind(2)+1:indp-1)); % this is the second number in the filename 
    
    % load the data 
    data = importdata(FileNamePath);
    % compute the mean (example) 
    Vector_mean_i(iFile) = mean(data); 
end

[Mathieu NOE]

FYI

this is the code for "natural" sorting of files

see attached the FEX files used in this script

% Folder = 'C:\Your\Folder';
Folder = cd;
FileList  = dir (fullfile(Folder, 'waveform_*.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);
    ind = findstr(FileName,'_');
    indp = findstr(FileName,'.txt');
    
    index1(iFile) = str2num(FileName(ind(1)+1:ind(2)-1)); % this is the first number in the filename 
    index2(iFile) = str2num(FileName(ind(2)+1:indp-1)); % this is the second number in the filename 
    
    % load the data 
    data = importdata(FileNamePath);
    % compute the mean (example) 
    Vector_mean_i(iFile) = mean(data); 
end

[Marco Pillon]

Hello,

the code allows you to import data in sequence but within a vector; instead it should place them inside an array.

That is, for example, the average of "wavefrom_5_2.txt" should occupy the element of row 5 and column 2 of the matrix.

Anyway thanks for showing me some commands I didn't know.

Thank you,

Marco

[Mathieu NOE]

hello Marco

try this :

% Folder = 'C:\Your\Folder';
Folder = cd;
FileList  = dir (fullfile(Folder, 'waveform_*.txt'));

% initialize array with large enough dimensions 
nn = numel(FileList);
Array_mean_i = zeros(nn,nn);

for iFile = 1:numel(FileList)
    FileName = FileList(iFile).name;
    FileNamePath = fullfile(Folder, FileName);
    ind = findstr(FileName,'_');
    indp = findstr(FileName,'.txt');
    
    index1(iFile) = str2num(FileName(ind(1)+1:ind(2)-1)); % this is the first number in the filename 
    index2(iFile) = str2num(FileName(ind(2)+1:indp-1)); % this is the second number in the filename 
    
    % load the data 
    data = importdata(FileNamePath);
    % compute the mean (example) 
    Array_mean_i(index1(iFile),index2(iFile)) = mean(data); 
       
end

% reduce array size to the right dimensions 
Array_mean_i = Array_mean_i(1:max(index1),1:max(index2));

[Marco Pillon]

Hello Mathieu,

I confirm that this code is correct and functional.

Thanks,

Marco

[Mathieu NOE]

Glad I could be of some help

have a good day !

[Stephen23]

@Mathieu NOE: I recommend sorting the structure itself:

FileList  = dir(fullfile(..));
FileList = natsortfiles(FileList); % sort file names into order

This has the benefit that NATSORTFILES can be simply commented out at any time, for any reason. It also means that all of the DIR data is available, e.g. file modification date, bytes, and folder path (since R2016b).

[Mathieu NOE]

hello Stephen

sure, that's what I already suggested in this post (my answer 10 May 2021 at 13:44) - see above

[Stephen23]

"sure, that's what I already suggested in this post (my answer 10 May 2021 at 13:44) - see above "

In that post you sorted just the filenames (as a cell array created from a comma-separated list):

FileList_sorted = natsortfiles({FileList.name});

I recommend simply sorting the entire structure, not just a cell array of filenames:

FileList = natsortfiles(FileList);

[Mathieu NOE]

OK tx for the tip - will try to remember this for next time ...