How to store a string data into an array

I have a an array like this:

trainLabels = zeros(315,1);

And I would like to put a string for example 'bass' on every element of that array. I tried using

fold = 'bass';
testLabels(testctr,1) = fold;

but its giving me this error:

Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-4.

Answer 1

[madhan ravi]

trainLabels = cell(315,1);
trainLabels(:)={'bass'}

[Janrex Pensader]

the fold variable is changing every time because it is in a loop and i need to store those into the array.

[madhan ravi]

ah then it would be

trainLabels{i} = {your variable}  % i is the loop iterator

[Janrex Pensader]

It's showing this error now

Unable to perform assignment because brace indexing is not supported for variables of this type.

[madhan ravi]

Ah upload your datas as a .mat file and upload the part of the code your trying to store datas

[Janrex Pensader]

the data that I need to store are foldernames ang here is my code:

files = dir('C:\Program Files\MATLAB\R2018a\bin\vision\data\');
files(ismember( {files.name}, {'.', '..'})) = [];
dirFlags = [files.isdir];
% Extract only those that are directories.
subFolders = files(dirFlags);
% Print folder names to command window.
trainctr =1;
testctr =1;
trainLabels = zeros(315,1);
testLabels = zeros(336,1);
trainingImages = zeros(32,32,3, 315);%315
testingImages = zeros(32,32,3, 336);%336

%subfolder loop
for k = 1 : length(subFolders)
  %FOR DEBUGGING: Print all subfolders
  %fprintf('Sub folder #%d = %s\n', k, subFolders(k).nametest(:,:,1,1));
  
  direc = 'C:\Program Files\MATLAB\R2018a\bin\vision\data\';
  newDir = strcat(direc,subFolders(k).name);
  
  subname = subFolders(k).name;
  %FOR DEBUGGING: Print new Directory 
  %fprintf('New Dir:  %s\n', newDir);
  
  scanDir = dir(newDir);
  scanDir(ismember( {scanDir.name}, {'.', '..'})) = [];
  scanFlags = [scanDir.isdir];
  scanSubFolders = scanDir(scanFlags);
    %note category loop
    for i = 1 : length(scanSubFolders)
        
        newDir2 = strcat(newDir,'\');
        newDir2 = strcat(newDir2,scanSubFolders(i).name);
        newDir3 = newDir2;
        newDir2 = strcat(newDir2,'\*.png');

        imagefiles = dir(newDir2);      
        nfiles = length(imagefiles);
        fprintf('%s',subFolders(k).name);
        fprintf('/');
        fprintf('%s\n',scanSubFolders(i).name);
        fold = scanSubFolders(i).name;
        %image loop
        for ii=1:nfiles
            fprintf('%s\n',imagefiles(ii).name);
            %
            
            photo=imagefiles(ii).name;
            filename = fullfile(newDir3,photo);
            Image = imread(filename);
            folder = strcmp('testing',subname);
            if folder == 1
                test(:,:,:,testctr) = Image;
                testLabels{testctr} = {fold};
                testctr = testctr+1;
            else
                train(:,:,:,trainctr) = Image;
                trainLabels{trainctr} = {fold};
                trainctr = trainctr+1;
            end
            
        end
        fprintf('\n');
    end
  fprintf('\n');         
end

[madhan ravi]

You didn't look into my answer properly! You forgot to add this line before the loop

trainLabels = cell(315,1);

[Janrex Pensader]

owhh sorry can you explain what that line will do?

[Janrex Pensader]

I added trainLabels = cell(315,1); at the top of the code and the error is gone but when i checked the elements of the array it shows this.

testLabels

testLabels =

  336×1 cell array

    {1×1 cell}
    {1×1 cell}
    {1×1 cell}
    {1×1 cell}...

[madhan ravi]

It's called preallocation it ensures that the variable is a cell array.

[madhan ravi]

celldisp(testLabels) %to view the contents of the cell

If my answered solved your question make sure to accept the answer and give a vote.

[Janrex Pensader]

are there any other ways to do this? because I'm going to connect this to a code that needs an ordinary array of names.

[madhan ravi]

"I'm going to connect this to a code that needs an ordinary array of names."

why not ? you can easily connect it

[Janrex Pensader]

The code I'm going to connect it to is the object detection sample code from mathworks.

https://www.mathworks.com/help/vision/examples/object-detection-using-deep-learning.html

My code will replace the loading of cifar data to the cnn. the trainLabels will replace the array trainingLabels, and testLabels will replace testingLabels. if i sue your solution for my probem will this code accept my array?

[madhan ravi]

To be frank and honest I don't have any experience with that field but in the link you suggested cell arrays ahd been used , why not try it and find it out?

[Janrex Pensader]

It didnt work it cause an error it shows "Invalid training data. Y must be a vector of categorical responses." where y is the trainingLabels