MATLAB Answers

How to read text files from different sub folders in a folder ?

185 views (last 30 days)
Luffy on 30 Sep 2015
Edited: Stephen Cobeldick on 16 Sep 2019
I have a collection of .txt files which are an output of a simulation software.The software puts the text files in different sub-folders within a folder.Is it possible to read all of those ?
For example:- In a single folder named top, there are 500 sub-folders(each subfolder is of format TC_SYS_01,TC_SYS_02,.....TC_SYS_500) with a text-file in each of them.I want to read those text files from each of those folders & do some operations.
I'm thinking of changing the simulation software code itself so that it outputs txt files within a folder(no sub-folders) & use this code:
F = dir('*.txt');
for i = 1:length(F)
text = fileread(F(i).name) ;
% Do further operations
but can i do it without changing the simulation software code and this : doesn't help me


Sign in to comment.

Accepted Answer

Image Analyst
Image Analyst on 30 Sep 2015
Not sure which code you used in that link, but you can use genpath() to generate a list of all subfolders, then use a loop to recurse into each of them. In the innermost for loop is where you'll process your text file. Try it - just copy and paste and it should work. Here is the code:
% Start with a folder and get a list of all subfolders.
% Finds and prints names of all text files in
% that folder and all of its subfolders.
% Similar to imageSet() function in the Computer Vision System Toolbox:
clc; % Clear the command window.
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
% Define a starting folder wherever you want
start_path = fullfile(matlabroot, '\toolbox');
% Ask user to confirm or change.
topLevelFolder = uigetdir(start_path);
if topLevelFolder == 0
% Get list of all subfolders.
allSubFolders = genpath(topLevelFolder);
% Parse into a cell array.
remain = allSubFolders;
listOfFolderNames = {};
while true
[singleSubFolder, remain] = strtok(remain, ';');
if isempty(singleSubFolder)
listOfFolderNames = [listOfFolderNames singleSubFolder];
numberOfFolders = length(listOfFolderNames)
% Process all text files in those folders.
for k = 1 : numberOfFolders
% Get this folder and print it out.
thisFolder = listOfFolderNames{k};
fprintf('Processing folder %s\n', thisFolder);
% Get filenames of all TXT files.
filePattern = sprintf('%s/*.txt', thisFolder);
baseFileNames = dir(filePattern);
numberOfFiles = length(baseFileNames);
% Now we have a list of all text files in this folder.
if numberOfFiles >= 1
% Go through all those text files.
for f = 1 : numberOfFiles
fullFileName = fullfile(thisFolder, baseFileNames(f).name);
fprintf(' Processing text file %s\n', fullFileName);
fprintf(' Folder %s has no text files in it.\n', thisFolder);


Show 1 older comment
Stephen Cobeldick
Stephen Cobeldick on 5 Mar 2018
@RC: so don't use uigetdir: use a hard-coded directory path, or pass the path as a function input argument, or get it from your UI, or whatever suits your operations.
Sam Webb
Sam Webb on 16 Jan 2019
This is brilliant code thank you, as this code answers alot of my questions about looping through subfolders and extracting information. However this code does not work on my macbook pro but will work nicely on my Windows 10 work computer, is there a reason why it may not work on Macs?
Image Analyst
Image Analyst on 16 Jan 2019
You don't need this code anymore since R2016b. You can use dir() with two asterisks, or use fileDatastore. See attached demo and see if it works with your Mac. If not, post your code in a new question.

Sign in to comment.

More Answers (3)

Meade on 2 Mar 2017
You can try the code below. It will do the same thing as Image Analyst's post, but is a little cleaner if you don't need any of the nested folder information, i.e. you only want the file paths.
mainFolder = uigetdir(); % Select your Main folder
[~,message,~] = fileattrib([mainFolder,'\*']);
fprintf('\n There are %i total files & folders.\n',numel(message));
allExts = cellfun(@(s) s(end-2:end),{message.Name},'uni',0);% Get file ext
TXTidx = ismember(allExts,'txt');% Search extensions for "CSV" at the end
TXT_filepaths = {message(TXTidx).Name}; % Use idx of TXTs to list paths.
fprintf('There are %i files with *.txt file ext.\n',numel(TXT_filepaths));
for ii = 1:numel(TXT_filepaths)
% Do import here


StephMarine on 16 Sep 2019
Do you know a way of using this if the file name has multiple . in it? the code runs well but reads the extension after the frist . so i have a few file names such as 000.111.222.csv so the ext is read as .111 any advice is appreciated!
Stephen Cobeldick
Stephen Cobeldick on 16 Sep 2019
"the code runs well but reads the extension after the frist "
There is nothing in this code that detects the period character, so it doesn't even know where the first period character is.
Note that the code is buggy as it incorrectly assumes that all file extensions have three characters: this can easily be fixed using fileparts.
"any advice is appreciated!"
Write simpler, more robust code using dir, fullfile, and fileparts.

Sign in to comment.

KSSV on 30 Sep 2015
You can get the names of the sub folders inside a folder using the following piece of code.
dirinfo = dir(pathfolder);
dirinfo(~[dirinfo.isdir]) = []; %remove non-directories
dirinfo(1:2) = []; % Remove the first two fields as they are . and ..
dirinfo is a structure with all the information. You can run a loop along this structure, go to the specific folder and then you can select the text files in it.

  1 Comment

Luffy on 30 Sep 2015
Thanks for the code.The above code gives the directory information in dirinfo variable. Now i know the names of all sub-folders. To access those text files i have to go inside each of those sub-folder,do text operations & go back to root directory.
For this i've tried:
length = numel(dirinfo);
for ii = 1:length
% folder name = dirinfo(ii).name
cd dirinfo(ii).name
% file operations
But i throws up an error:- Error using cd; name is non-existent or not a directory*

Sign in to comment.

Thorsten on 30 Sep 2015
filenames = getAllFiles('.', '*.txt', 1);
and then loop through the filenames and work on them; you do not need to cd to the directories.


Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!