Cant change directory between loops

I am trying to change files between loops and read in the images from each, however only the images from the first file are ever read in. Apologies if this has been asked before, I couldnt find anything similar when looking for a solution.

for j = 1:5
    
    ds = sprintf("J:\\Images\\BCS %d", j);
    dsn = dir(ds);
    dataset=dsn(~ismember({dsn.name},{'.','..'}));
    
    for i = 1:length(dataset)
        
        img = dataset(i).name;
        imgr = imread(img);
        imshow(imgr)
        stats = regionprops(imgr, 'all');
        
        allPerimeters = [stats.Perimeter];
        allAreas = [stats.Area];
        allCircularities(i, j) = allPerimeters  .^ 2 ./ (4 * pi* allAreas);
        
    end
end

Answer 1

[Walter Roberson]

img = fullfile(dataset(i).folder,dataset(i).name);

[Stephen23]

img = fullfile(dataset(i).folder,dataset(i).name);
                      ^^^

[Walter Roberson]

@Stephen You are right, I fixed it now.

Answer 2

[Jon]

Looking at your loops the logic seems basically OK but I can't run it to see exactly what happens as I don't have your image directories.

I would suspect that you are not really getting back a full list of all of the files in each directory you are looping through. So in particular you should check that the results of

dsn = dir(ds);

are what you expect. If not look one line earlier and see whether the string ds is really what you want. It looks like it evaluates to something like, for example with j = 3

ds = "J:\Images\BCS 3"

Is that the name of a folder full of images?

Note when providing code you can use the code button in the Answers toolbar to format it nicely.

Also when you do your directory search you can use wildcard characters, like J:\Images\myImages\*.jpg to just get jpegs or whatever.Then you don't have to get rid of the . and .. in your results.

Answer 3

[yanqi liu]

for j = 1:5    
    ds = sprintf("J:\\Images\\BCS %d", j);
    dsn = dir(ds);
    dataset=dsn(~ismember({dsn.name},{'.','..'}));    
    for i = 1:length(dataset)
        if dataset(i).isdir == 1
            continue;
        end    
        img = fullfile(dataset(i).folder,dataset(i).name);
        imgr = imread(img);
        figure(1); clf; imshow(imgr, [])
        stats = regionprops(imgr, 'all');    
        allPerimeters = [stats.Perimeter];
        allAreas = [stats.Area];
        allCircularities{i, j} = allPerimeters  .^ 2 ./ (4 * pi* allAreas);    
    end
end

[Walter Roberson]

for j = 1:5    
    ds = sprintf("J:\\Images\\BCS %d", j);
    dsn = dir(ds);
    dataset = dsn(~[dsn.isfolder]);  %also deals with . and ..
    for i = 1:length(dataset)
        img = fullfile(dataset(i).folder,dataset(i).name);
        imgr = imread(img);
        figure(1); clf; imshow(imgr, [])
        stats = regionprops(imgr, 'all');    
        allPerimeters = [stats.Perimeter];
        allAreas = [stats.Area];
        allCircularities{i, j} = allPerimeters  .^ 2 ./ (4 * pi* allAreas);    
    end
end

[Stephen23]

dataset = dsn(~[dsn.isfolder]);
%         ^^^