How to bypass a directory that is not exist?

My experiment contains my subjects data and each subject consists of different blocks, before I do the analysis I need to merge my data into one mat file, so first I need to load all of the data, but the problem is some of my subjects have missing blocks and when my codes want to read all data, It crashes and said ''Unable to read file 'Subject 1 Block 3.mat'. No such file or directory'' , so I need to bypass the data that their directory doesn't exist, so I wrote this if statement inside my code but it didn't work:

%load data
s_Initial = 1;
s_Final = 100;
B_Initial = 1;
B_Final = 3;
% merging Data
Subjects_ID = [];
Block_ID = [];
% merge Data
for subject_Counter = s_Initial: s_Final
    for block_Counter = B_Initial: B_Final
        % load the directory name
        load_Data = fullfile(append('Subject', ' ',num2str(subject_Counter),...
            ' ', 'Block',' ',num2str(block_Counter),'.mat'));
        if class(load_Data) == 'char'
             all_Subjects(block_Counter, subject_Counter) = load(load_Data);
        else 
             break ;
        end
        Subjects_ID = [Subjects_ID; subject_Counter];
        Block_ID = [Block_ID; block_Counter];
    end
end
save('all_Subjects')

Answer 1

[Ameer Hamza]

See exist() function https://www.mathworks.com/help/releases/R2020a/matlab/ref/exist.html. Call it with with search type 'file'

if exist(load_Data, 'file')

[Ali Motahharynia]

Thanks for your answer, this works really nice.

Answer 2

[Image Analyst]

Try isfile():

%load data
s_Initial = 1;
s_Final = 100;
B_Initial = 1;
B_Final = 3;
% merging Data
Subjects_ID = [];
Block_ID = [];
% merge Data
for subject_Counter = s_Initial: s_Final
	for block_Counter = B_Initial: B_Final
		% load the directory name
		load_Data = fullfile(append('Subject', ' ',num2str(subject_Counter),...
			' ', 'Block',' ',num2str(block_Counter),'.mat'));
		if isfile(load_Data)
			% If the file actually exists.
			all_Subjects(block_Counter, subject_Counter) = load(load_Data);
			Subjects_ID = [Subjects_ID; subject_Counter];
			Block_ID = [Block_ID; block_Counter];
		end
	end
end
save('all_Subjects')

[Ali Motahharynia]

Thanks for your answer, this works really nice. Is there anyway I also select this answer as accepted answer? Cause both exist and isfile works perfectly.

[Image Analyst]

isfile() is the newer, preferred way of doing it. You can only accept one answer however you can "Vote" for any number of answers to award the answerer "reputation points." Thanks in advance. 😊

[Ali Motahharynia]

Thank you for informing me, and I already voted for your nice answer,

I also have another problem for the next lines of this code and I already asked that in mathwork, I will appreciate it if you take a look at that at this link, Thank you in advance. 😊

https://www.mathworks.com/matlabcentral/answers/539935-how-to-bypass-empty-fields-in-structure-when-loading-data?s_tid=prof_contriblnk