Developing and testing your own algorithms
The PRT provides support for incorportating your own algorithms into the PRT framework with relative ease. Template classes are provided for classifiers, clustering, kernels, outlier removal, pre processing, and regression.
Contents
An Example
As an example, type
prtNewClass
and enter "prtClassMine" when prompted by the dialog. Press save, and a skeleton classifier file will open in the MATLAB editor. This M-file will contain instructions for creating your own classification object.
Consider a simple classifier, a generalized likelihood ratio test (GLRT), where the two classes are described by multivariate normal random variables. Such a classifier would have two parameters, a random variable describing each class. So, to construct a classifier object with these parameters, in the file prtClassMine, under properties, you would place the following definitions:
rvH0 = prtRvMvn; % Mean and variance of H0 rvH1 = prtRvMvn; % Mean and variance of H1
A GLRT classifier must estimate these two random variables. This happens during the TRAIN operation. So, for the trainAction code, you would use the following code:
self.rvH0 = mle(self.rvH0, dataSet.getObservationsByClassInd(1)); self.rvH1 = mle(self.rvH1, dataSet.getObservationsByClassInd(2));
The above code would learn the maximal likelhiood estimates of both random variables from the training data.
Finally, for a trained classifier, you will need code that outputs a decision statistic. So for the runAction, place the following code:
logLikelihoodH0 = logPdf(self.rvH0, dataSet.getObservations()); logLikelihoodH1 = logPdf(self.rvH1, dataSet.getObservations()); dataSet = dataSet.setObservations(logLikelihoodH1 - logLikelihoodH0);
Save your M-file and you now have a new prtClass object that can be used like any other prtClass object in the toolbox. It will be fully compatible with prtAlgorithms and all other features of the PRT.
Test suite for the PRT
A full test suite for the PRT is also provided. You can access it in the prtRoot\]internal\test directory. Upon intallation, you might want to run the full suite with the command prtTest. If you find yourself modifying the provided functions, it is a good idea to run this test from time to time to ensure nothing has broken. An abbreviated test, prtTestSmoke, is also provided. prtTestSmoke runs a small subset of the test suite, and is designed to quickly test the major features of the product.