How to loop through a folder?
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I currently have 24 folders within a folder and I was wondering if it was possible to loop through the 24 folders and extract information from a subfolder within the 24 folders.
1 个评论
Brando Miranda
2018-3-30
great question. This is some of the trivialest things to do in a language and its incomprehensible how hard it is to do in matlab.
回答（3 个）
Image Analyst
2014-3-11
4 个投票
See my attached demo where it recurses through a folder and all subfolders.
13 个评论
N
2014-6-11
hi I love your code. I do have a question with it. If I would like to save the fullFileName, so it doesn't get overwritten every time, how would i do it?
Image Analyst
2014-6-11
Make it a cell array
fullFileName{counter} = fullfile(thisFolder, baseFileNames(f).name);
counter = counter + 1;
N
2014-6-11
If I do this, I get the error:
Cell contents assignment to a non-cell array object.
Image Analyst
2014-6-11
Worked fine for me. See attachment.
N
2014-6-14
thanks it works for me now too !
Mor H
2016-7-4
Thanks a lot !
Arantza Dobbels
2016-7-6
Hey guys! this is exactly the code that I need but for some reason when I try to run it, it says the number of folders is 1 and then says that there are no files in the subfolders. What am I doing wrong? Thanks!
Vanessa Machuca
2017-6-16
编辑：Vanessa Machuca
2017-6-16
I'm facing the same issue as Arantza. :(
Image Analyst
2017-6-16
I made a newer one to use the new capabilities of dir() to use to recurse into subfolders. Try it. It's attached. Works for Release R2016b and later.
Brando Miranda
2017-12-20
do you a non recursive version?
Image Analyst
2017-12-20
Not sure what you're looking for. The program itself is not recursive - it uses the standard capability of the built-in dir() function. What I meant by recursive is that it finds files in folder, and in subfolders of those folder, and in subfolders of those subfolders, etc. until you've reached the deepest level of the directory tree.
What kind of problem are you having with the program such that you wanted to ask that question?
Rik
2020-12-10
You can use the ** option of dir. What did you try?
Image Analyst
2020-12-10
Yes, essentially it's
filePattern = sprintf('%s/**/*.*', topLevelFolder);
allFileInfo = dir(filePattern);
See my attached m-file for a full demo with tons of explanations.
Sean de Wolski
2014-3-11
编辑：Sean de Wolski
2014-3-11
You can use the dir command to give you the names and then loop over them.
files = dir;
directoryNames = {files([files.isdir]).name};
directoryNames = directoryNames(~ismember(directoryNames,{'.','..'}))
Now run the for-loop over directoryNames and apply your analysis to each
7 个评论
andrew
2014-3-11
Sean de Wolski
2014-3-11
Loop over the directory and use a wildcard inside of dir to grab all of the csv files. Something like
dir([directory '\*.csv'])
andrew
2014-3-11
编辑：Walter Roberson
2014-3-11
Walter Roberson
2014-3-11
Note: fullfile() is better practice than concatenating file substrings.
And if you were to construct the specification as a variable you could then
ls(TheVariable)
to see if the files are found that way.
Brando Miranda
2018-3-30
why does
directories_names_list = dir('noise*')
for expt_dir = directories_names_list.name
not work?
Brando Miranda
2018-3-30
why does
directoryNames = {files([files.isdir]).name};
work? its really cryptic? are u using list comprehensions or what dark magic is going on there?
@Brando Miranda: "list comprehensions" exist only in Python. They do not exist in MATLAB.
manideep reddy
2018-4-18
see my code below but make sure that the folder which we are looping through contains only flolders and not files.
cd pwd ; ## Or any other working directory you want
X = ls ;
disp(X) ;
for itr = 1:size(X)(1)
string_1 = X(itr,:) ;
string_2{itr} = deblank(string_1) ; ## This deletes the trailing blank spaces
end
for itr = 1:size(X)(1)
cd(string_2{itr})
cd ../
# DO SOMETHING #
end
end2 个评论
This code has several bugs and could be significantly improved:
- Do NOT use cd. Using cd is slower than using absolute/relative filepaths, makes debugging more difficult, and changes which functions/scripts are accessible to MATLAB. It is NOT necessary to cd directories where datafiles are stored because all MATLAB filereading/writing functions accept relative/absolute paths. Basically cd should only be used interactively, and NOT used in code. See:
- Do NOT use ls for parsing filenames. This operator is intended for displaying a list in the command window, but parsing its output char array is a waste of time. dir is what the MATLAB documentation recommends and shows in all examples that require reading multiple files from a folder, e.g.:
- size(X)(1) is not valid MATLAB syntax, and will throw an error.
- string_2 is not preallocated.
- A loop is anyway not required for deblanking the filenames: simply use deblank(cellstr(X)).
Rather than following this buggy code, I recommend that other users follow the examples shown in the MATLAB help and wiki:
manideep reddy
2018-4-20
Thank you very much. I am actually not a computer science student. So, just answered the query without considering algorithm and complexity. Anyway, I will implement your suggestions/ recommendations in future. Thanks..!
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2020-12-10
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