How to delete all files with a certain extension?

I have a directory with several .png files that I would like to delete in a script. I have the following script that I have modified from a script I found in the Matlab forums:

d = dir(file_path);
file_names = {d.name}';
count = 1;
for jj = 1:length(file_names)
	pngFilePattern = char(fullfile(file_path,'*.png'));
	pngFiles = dir(pngFilePattern);
	count = 1;
	for kk = 1:length(pngFiles)
		pngBaseFileName = pngFiles(kk).name;
		pngFullFileName = fullfile(pngFiles(kk).folder,pngBaseFileName);
		delete(pngFullFileName)
	end
	count = count + 1;
end

I've simplied this script by just using "file_path" in this forum post instead of the full path of the file. This code seems to work (all my .png files get deleted), but I think I may have a problem in this script because I can't get "count" to equal the number of files in the directory that I want to delete. The final value of "count" is several multiples of the number of .png files that need to be deleted.

Can someone please tell me how I can modify (and hopefully simplify) this script, so I can make sure that only the .png files that to be deleted are deleted?

Thank you!

Answer 1

[dpb]

Because your count variable is being incremented in the outer loop which is running over a dir() list of all files (including subdirectory names and the two "dot" directory entries), not just over the *.png files.

If you're only worried about the single directory, you don't need (and don't want) the outer loop; just use

pngFiles=dir(fullfile(file_path,'*.png');
count = numel(pngFiles);
for i=1:count
	delete(fullfile(pngFiles(i).folder,pngFiles(i).name);
end

But, you don't need to iterate over all files, simply

delete *.png

will do the trick in the current directory or

delete(fullfile(fullfile(file_path,'*.png'))

wipes 'em all out in the subject directory.

[Allen Hammack]

Thank you for your help!

I'm trying your last command, but I'm having trouble. I've tried the following from the Matlab Command Window:

>> fullfile(pwd,input_all_single_test{1}.raw_data_daily_directory,input_all_single_test{1}.daily_test_directories(k))

ans =

  1×1 cell array

    {'F:\Projects 3-12-21\Pittsburgh - Upper Ohio\FE System\Technical\Model Operation and Data\Plan C\20220607\MNTFEPLANC-224-202206071441'}

>> char(fullfile(pwd,input_all_single_test{1}.raw_data_daily_directory,input_all_single_test{1}.daily_test_directories(k)))

ans =

    'F:\Projects 3-12-21\Pittsburgh - Upper Ohio\FE System\Technical\Model Operation and Data\Plan C\20220607\MNTFEPLANC-224-202206071441'

>> delete(char(fullfile(pwd,input_all_single_test{1}.raw_data_daily_directory,input_all_single_test{1}.daily_test_directories(k))),'*.png')
Warning: 'F:\Projects 3-12-21\Pittsburgh - Upper Ohio\FE System\Technical\Model Operation and Data\Plan C\20220607\MNTFEPLANC-224-202206071441' is a directory.  Use
rmdir to delete directories. 

The .png files I want to delete are definitely in the MNTFEPLANC-224-202206071441 directory, but I can't figure out what I'm doing wrong. Do you see what I'm messing up?

Thank you!

[Stephen23]

"Do you see what I'm messing up?"

You omitted '*.png' from the FULLFILE command.

(it is not an input to the DELETE command as you attempted)

[Allen Hammack]

That fixed my problem! Thank you!