MATLAB: Check if a file exists

text file

I'm using the "importdata" function to import data from a text file. I would like to have a way to check if the text file exists before attempting to import data from the file. If the file doesn't exist, I would then like to display a custom error message. What is the function that I should use?

Best Answer

Starting in R2017b, you can use the "isfile" function to check if a file exists. For example:

if isfile(filename)
     % File exists.

else
     % File does not exist.

end

The "isfile" function searches for files only on the specified path or in the current folder.

For R2017a and previous releases, use the "exist" function. For example:

if exist(filename, 'file') == 2
     % File exists.
else
     % File does not exist.
end

Be sure to specify an absolute path for the file name. The "exist" function searches all files and folders on the search path, which can lead to unexpected results if multiple files with the same name exist.

Related Solutions

MATLAB: How to check if a directory(folder) exists

well, I suppose you want to create if it doesn't exist, after checking... so you could do it like that:

    if ~exist(yourFolder, 'dir')
       mkdir(yourFolder)
    end

It basically check if youFolder does not exist. If that's true, it creates youFolder.

Cheers.

MATLAB: I have a folder of .tif images that need to be converted to a different format for downstream analysis

Hi,

I think your input tif files are in single format whereas your output file format which is jpeg doesn't support single format while using imwrite (you can find using help imwrite in the 'fmt' of the file output section)

You can do this instead. either save them in a different file format let us say 'bmp', 'jp2' or 'png'. Else you can do the following thing by converting your input image from single format to unsigned integer 8 (uint8).

% Specify the folder where the files live.
myFolder = '/Users/masonlien/Desktop/PhD/Drone/2020/test';
% Check to make sure that folder actually exists.  Warn user if it doesn't.
if ~isfolder(myFolder)
	errorMessage = sprintf('Error: The following folder does not exist:\n%s\nPlease select another folder.', myFolder);
	uiwait(warndlg(errorMessage));
	myFolder = uigetdir();
end
% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(myFolder, '*.tif'); % Change to whatever pattern you need.
theFiles = dir(filePattern);
numFiles = length(theFiles);
if numFiles == 0
	warningMessage = sprintf('Warning: no TIFF images found in the folder:\n%s', myFolder);
	uiwait(warnuser(warningMessage));
	return;
end
for k = 1 : numFiles
	baseFileName = theFiles(k).name;
	fullFileName = fullfile(myFolder, baseFileName);
	fprintf('Now reading %s (#%d of %d).\n', fullFileName, k, numFiles);
    % such as reading it in as an image array with imread()
    
    % Change made here 
	imageArray = uint8(imread((fullFileName)));
	imshow(imageArray);  % Display image.
	caption = sprintf('%s (#%d of %d)', fullFileName, k, numFiles);
	title(caption, 'FontSize', 14, 'Interpreter', 'none');
	drawnow; % Force display to update immediately.
	% Write it out as a PNG file.
	baseFileName = strrep(lower(baseFileName), '.tif', '.jpg');
	outputFileName = fullfile(myFolder, baseFileName);
	fprintf(1, 'Now writing %s\n', outputFileName);
 	imwrite(imageArray, outputFileName);
end

Best Answer

Related Solutions

MATLAB: How to check if a directory(folder) exists

MATLAB: I have a folder of .tif images that need to be converted to a different format for downstream analysis

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