prtScoreRoc   Generate a reciever operator characteristic curve
 
     prtScoreRoc(DECSTATS,LABELS) plots the receiver operator
     characteristic curve for the decision statistics DECSTATS and the
     corresponding labels LABELS. DECSTATS must be a Nx1 vector of decision
     statistics. LABELS must be a Nx1 vector of binary class labels.
 
     [PF, PD, THRESHOLDS, AUC] = prtScoreRoc(DECSTATS,LABELS) outputs the
     probability of false alarm PF, the probability of detection PD, the
     THREHSOLDS required to achieved each PF and PD, and the area under the
     ROC curve AUC.
 
     [PF, PD, THRESHOLDS, AUC] = prtScoreRoc(DECSTATSMAT,LABELS) outputs
     the roc outputs for each column of DECSTATSMAT using. The output
     values are now cell arrays containing the outputs as if prtScoreRoc
     were called on each column of DECSTATSMAT individually.
 
     [...] = prtScoreRoc(PRTDATASETCLASS) use a prtDataSetClass as input
     DECSTATS is PRTDATASETCLASS.getObservations() and LABELS is
     PRTDATASETCLASS.getTargets(). If PRTDATASETCLASS.nFeatures > 1 cell
     arrays are provided as outputs.
 
 
     Example:
     TestDataSet = prtDataGenSpiral;       % Create some test and
     TrainingDataSet = prtDataGenSpiral;   % training data
     classifier = prtClassSvm;             % Create a classifier
     classifier = classifier.train(TrainingDataSet);    % Train
     classified = run(classifier, TestDataSet);
     %  Plot the ROC
     prtScoreRoc(classified.getX, TestDataSet.getY);