DownloadCIFAR10.m error while I try to prepare the CIFAR10 dataset.

I tried to create a new script called DownloadCIFAR10.m and copied a code from: https://www.mathworks.com/matlabcentral/mlc-downloads/downloads/submissions/62990/versions/3/previews/DeepLearningDemos/DownloadCIFAR10.m/index.html as shown below:

%% Download the CIFAR-10 dataset
if ~exist('cifar-10-batches-mat','dir')
    cifar10Dataset = 'cifar-10-matlab';
    disp('Downloading 174MB CIFAR-10 dataset...');   
    websave([cifar10Dataset,'.tar.gz'],...
        ['https://www.cs.toronto.edu/~kriz/',cifar10Dataset,'.tar.gz']);
    gunzip([cifar10Dataset,'.tar.gz'])
    delete([cifar10Dataset,'.tar.gz'])
    untar([cifar10Dataset,'.tar'])
    delete([cifar10Dataset,'.tar'])
end    
   
%% Prepare the CIFAR-10 dataset
if ~exist('cifar10Train','dir')
    disp('Saving the Images in folders. This might take some time...');    
    saveCIFAR10AsFolderOfImages('cifar-10-batches-mat', pwd, true);
end

I can download the dataset but when I try to prepare it I get this error: Undefined function or variable 'saveCIFAR10AsFolderOfImages'.

Please help

Thanks in advance....

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/mlc-downloads/downloads/submissions/62990/versions/3/previews/DeepLearningDemos/saveCIFAR10AsFolderOfImages.m/index.html

[Nasir Sinani]

Thank you!

[Melvyn Smith]

That's an answer?

[Walter Roberson]

Yes, it is an answer. The poster was missing a particular function so I posted a link to the exact function that they needed.

The broader issue was probably that they did not download the entire file exchange contribution and add it to their matlab path. However I have encountered enough instances in which a user claims to have taken that step but still cannot find the file that I do not always feel like arguing with users to look more closely; sometimes it is much easier to simply provide the link directly to a file that a user is having trouble finding. Users have expressed that they feel that I am patronizing them when I push them to find the missing file on their own system instead of just providing the file for them.

What is your suggestion on how to deal with situations such as this?

[Akhil Anchan]

Where do I implement the saveCIFARcode in this program?

%% Download the CIFAR-10 dataset
if ~exist('cifar-10-batches-mat','dir')
    cifar10Dataset = 'cifar-10-matlab';
    disp('Downloading 174MB CIFAR-10 dataset...');   
    websave([cifar10Dataset,'.tar.gz'],...
        ['https://www.cs.toronto.edu/~kriz/',cifar10Dataset,'.tar.gz']);
    gunzip([cifar10Dataset,'.tar.gz'])
    delete([cifar10Dataset,'.tar.gz'])
    untar([cifar10Dataset,'.tar'])
    delete([cifar10Dataset,'.tar'])
end    
   function saveCIFAR10AsFolderOfImages(inputPath, outputPath, varargin)
   
% saveCIFAR10AsFolderOfImages   Save the CIFAR-10 dataset as a folder of images
%   saveCIFAR10AsFolderOfImages(inputPath, outputPath) takes the CIFAR-10
%   dataset located at inputPath and saves it as a folder of images to the
%   directory outputPath. If inputPath or outputPath is an empty string, it
%   is assumed that the current folder should be used.
%
%   saveCIFAR10AsFolderOfImages(..., labelDirectories) will save the
%   CIFAR-10 data so that instances with the same label will be saved to
%   sub-directories with the name of that label.

% Check input directories are valid
if(~isempty(inputPath))
    assert(exist(inputPath,'dir') == 7);
end
if(~isempty(outputPath))
    assert(exist(outputPath,'dir') == 7);
end

% Check if we want to save each set with the same labels to its own
% directory.
if(isempty(varargin))
    labelDirectories = false;
else
    assert(nargin == 3);
    labelDirectories = varargin{1};
end

% Set names for directories
trainDirectoryName = 'cifar10Train';
testDirectoryName = 'cifar10Test';

% Create directories for the output
mkdir(fullfile(outputPath, trainDirectoryName));
mkdir(fullfile(outputPath, testDirectoryName));

if(labelDirectories)
    labelNames = {'airplane','automobile','bird','cat','deer','dog','frog','horse','ship','truck'};
    iMakeTheseDirectories(fullfile(outputPath, trainDirectoryName), labelNames);
    iMakeTheseDirectories(fullfile(outputPath, testDirectoryName), labelNames);
    for i = 1:5
        iLoadBatchAndWriteAsImagesToLabelFolders(fullfile(inputPath,['data_batch_' num2str(i) '.mat']), fullfile(outputPath, trainDirectoryName), labelNames, (i-1)*10000);
    end
    iLoadBatchAndWriteAsImagesToLabelFolders(fullfile(inputPath,'test_batch.mat'), fullfile(outputPath, testDirectoryName), labelNames, 0);
else
    for i = 1:5
        iLoadBatchAndWriteAsImages(fullfile(inputPath,['data_batch_' num2str(i) '.mat']), fullfile(outputPath, trainDirectoryName), (i-1)*10000);
    end
    iLoadBatchAndWriteAsImages(fullfile(inputPath,'test_batch.mat'), fullfile(outputPath, testDirectoryName), 0);
end
end

function iLoadBatchAndWriteAsImagesToLabelFolders(fullInputBatchPath, fullOutputDirectoryPath, labelNames, nameIndexOffset)
load(fullInputBatchPath);
data = data'; %#ok<NODEF>
data = reshape(data, 32,32,3,[]);
data = permute(data, [2 1 3 4]);
for i = 1:size(data,4)
    imwrite(data(:,:,:,i), fullfile(fullOutputDirectoryPath, labelNames{labels(i)+1}, ['image' num2str(i + nameIndexOffset) '.png']));
end
end

function iLoadBatchAndWriteAsImages(fullInputBatchPath, fullOutputDirectoryPath, nameIndexOffset)
load(fullInputBatchPath);
data = data'; %#ok<NODEF>
data = reshape(data, 32,32,3,[]);
data = permute(data, [2 1 3 4]);
for i = 1:size(data,4)
    imwrite(data(:,:,:,i), fullfile(fullOutputDirectoryPath, ['image' num2str(i + nameIndexOffset) '.png']));
end
end

function iMakeTheseDirectories(outputPath, directoryNames)
for i = 1:numel(directoryNames)
    mkdir(fullfile(outputPath, directoryNames{i}));
end
end

%% Prepare the CIFAR-10 dataset
if ~exist('cifar10Train','dir')
    disp('Saving the Images in folders. This might take some time...');    
    saveCIFAR10AsFolderOfImages('cifar-10-batches-mat', pwd, true);
end

[Walter Roberson]

Grab the file I linked to and store it as saveCIFAR10AsFolderOfImages.m in the same directory that you have the other code.