facing issue to show images from folder.

outputFolder = fullfile('caltech101');
rootFolder = fullfile(outputFolder,'ObjectCategories');

categories = {'airplanes','ferry','laptop'};

imds = imageDatastore(fullfile(rootFolder,categories),'LabelSource','foldernames','IncludeSubfolders',true);
tbl = countEachLabel(imds);
minSetCount = min(tbl{:,2});

imds = splitEachLabel(imds, minSetCount, 'randomize');
countEachLabel(imds)

airplanes = find(imds.Labels =='airplanes',1);
ferry = find(imds.Labels =='ferry',1);
laptop = find(imds.Labels =='laptop',1);

figure
subplot(2,2,1);
imshow(readimage(imds,airplanes));

subplot(2,2,2);
imshow(readimage(imds,ferry));

subplot(2,2,3);
imshow(readimage(imds,laptop));

ERROR:

Subscript indices must either be real positive
integers or logicals.

Error in classification (line 21)
imshow(readimage(imds,airplanes));

[Geoff Hayes]

You may need to use the MATLAB debugger to see what the values are for imds and airplanes. Is the latter a positive integer? Also, is this line of code

imds.Labels =='airplanes'

valid when comparing the labels with a string? Or do you need to use a strcmp?

Answer 1

[Jan]

Use the debugger to find the cause of errors. Type this in the command window:

dbstop if error

Then run the code again. When Matlab stops at the error, check the values of the locally used variables. Here I guess, that you have redefined "readimage" by a variable:

which('readimage')

Geoff's idea is important also: The == operator works with string array, but not with char vectors. For the latter it is an elementwise comparison of the characters. Use strcmp instead.