prtClassKnn  K-nearest neighbors classifier
 
     CLASSIFIER = prtClassKnn returns a K-nearest neighbors classifier
 
     CLASSIFIER = prtClassKnn(PROPERTY1, VALUE1, ...) constructs a
     prtClassKnn object CLASSIFIER with properties as specified by
     PROPERTY/VALUE pairs.
 
     A prtClassKnn object inherits all properties from the abstract class
     prtClass. In addition is has the following properties:
 
     k                  - The number of neigbors to be considered
     distanceFunction   - The function to be used to compute the
                          distance from samples to cluster centers. 
                          It must be a function handle of the form:
                          @(x1,x2)distFun(x1,x2). Most prtDistance*
                          functions will work.
 
     For information on the  K-nearest neighbors classifier algorithm, please
     refer to the following URL:
 
     http://en.wikipedia.org/wiki/K-nearest_neighbor_algorithm    
 
     A prtClassKnn object inherits the TRAIN, RUN, CROSSVALIDATE and
     KFOLDS methods from prtAction. It also inherits the PLOT method
     from prtClass.
 
     Example:
 
      TestDataSet = prtDataGenUnimodal;      % Create some test and 
      TrainingDataSet = prtDataGenUnimodal;  % training data
      classifier = prtClassKnn;           % Create a classifier
      classifier = classifier.train(TrainingDataSet);    % Train
      classified = run(classifier, TestDataSet);         % Test
      classifier.plot;