how to create a target set for ANN classification???

i am trying to create a target set for my inputs to be used in classification with ANN but i have some challenges . i have 23 classes of images of which each class contains 100 images. feature extraction was done and i got a matrix of 2300*20736. how can i create a target set for my inputs.

Answer 1

[Baptiste Ottino]

Your target set must have one label for each sample, so it must contains 2300 elements. Here is an easy way to build one. Start by numbering your classes from 1 to 23. Make sure that your X Array is sorted by class, meaning all the samples from the first class, then all the samples from the second class, and so on. Then:

 % Classes from 1 to 23
 y = 1:23;

 % 100 samples per class
 y = repmat(y, 100, 1);

 % Reshape to obtain a vector
 y = reshape(y, 1, numel(y));

At this stage, you should have a 1-by-2300 vector with numeric class labels from 1 to 23. This is what you want if you use the Statistics and Machine Learning tToolbox.

Now, I suppose you intend to use the Neural Network Toolbox. In that case the syntax is a bit different: the class labels are in a 23-by-2300 matrix, each column being a sample, with the row corresponding to the class getting value '1' and the rest '0'. To build it from the previous syntax, type:

 y = full(ind2vec(y));

Good luck!

[julius bamwenda]

thanks so much. İt has really helped.

[julius bamwenda]

Hi everyone, i have applied ANN and i have successfully got good results. so now i want to apply KNN classification method on the same data. as far as KNN is concerned, i have to create a training set, sample set and lastly the group set. ie: class=knnclassify(sample,training,group). so how can i create those sets? thanks in advance

[shivasmic]

Baptiste ottino, thanx for the method, the method that you suggest for the comnstruction of target vector leads to the creation of matrix which has dimensions of 23 x 2300 but the input vector has dimension of 2300 x 20736.

Dont you think that the dimension of target vector should also be 2300 x 23.

I am asking this as I am also facing the same problem. Kindly clarify this as soon as possible!