Unable to perform assignment because the size of the left side is 1-by-7056 and the size of the right side is 1-by-213444

Hello,

I am writing a code to extract HOG features with the hope of using MATLAB to recognize a picture taken with a webcam. The code that I am having trouble with is code that is borrowed from the Face Recognition with MATLAB seminar by Avi Nehemiah. My pertinent code is as follows:

faceDatabase = imageSet('MarioImageDatabase',"recursive");

training=faceDatabase;

trainingFeatures = zeros(size(training,2)*training(1).Count,7056);
featureCount = 1;
for i=1:size(training,2)
    for j = 1:training(i).Count
        trainingFeatures(featureCount,:) = extractHOGFeatures(read(training(i),j));
        trainingLabel{featureCount} = training(i).Description;    
        featureCount = featureCount + 1;
    end
    personIndex{i} = training(i).Description;
end

faceClassifier1=fitcecoc(trainingFeatures,trainingLabel)

I am getting the error "Unable to perform assignment because the size of the left side is 1-by-7056 and the size of the right side is 1-by-213444"

The problem is with the line:

trainingFeatures(featureCount,:) = extractHOGFeatures(read(training(i),j));

I have tried changing the number of the .Count in the "trainingFeatures=zeros..." line, but if I change it to 213444 it says the left side is 213444 and the right side is 7056. So it appears that the numbers can be changed, I am just unsure how to get them to equal one another.

For reference, the image set is 3 photos.

The variables in my workspace and their values are as follows:

faceDatabase 1x1 imageSet

featureCount 1

i 1

j 1

training 1x1 imageSet

trainingFeatures 3x213444 double

if I change the .Count to 7056 then the trainingFeatures variable is 3x7056 double

Can you please help me make this work? Thank you in advance.

Answer 1

[KSSV]

The error is clear..you have initiliazed a array with smaller dimension and you are trying to save more elements in the array.

Example:

A = zeros(3) ;
A(1,:) = rand(1,4) ;  % this is error, you have to save array of size 1*3

If you know that dimensions are always same than you have to initialize as:

A = zeros(4) ; 
A(1,:) = rand(1,4) ; 

If you don't know the dimensions of the array, you initialize them as cell.

A = cell(4,1) ; 
A{1} = rand(1,3) ;
A{2} = rand(1,4) ; 

[Conan Curry]

Thank you so much for your helpful reply. Unfortunately I am still having trouble figuring out from your example what exaclty in my code I need to change. Could you please point it out in my code if you have the time, and what I should change it to? Thank you again.

[KSSV]

trainingFeatures = zeros(size(training,2)*training(1).Count,213444);

The above works if all the data which you try to save have dimension of 1*213444.

If not

trainingFeatures = cell(size(training,2)*training(1).Count,1);
featureCount = 1;
for i=1:size(training,2)
    for j = 1:training(i).Count
        trainingFeatures{featureCount} = extractHOGFeatures(read(training(i),j));
        trainingLabel{featureCount} = training(i).Description;    
        featureCount = featureCount + 1;
    end
    personIndex{i} = training(i).Description;
end

[Conan Curry]

Okay wonderful, thank you so much. I have tried those modifications and gotten the following;

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

trainingFeatures{featureCount}=extractHOGFeatures(read(training(i),j))

Do you have any suggestions on how to fix that please?

[KSSV]

Did you use this line?

trainingFeatures = cell(size(training,2)*training(1).Count,1);

[Conan Curry]

Oh! I missed putting 'cell' in. Thank you so much!!