prtDataSetBase    Base class for all prt data sets.
 
  This is an abstract class from which all prt data sets inherit from.
  It can not be instantiated. It contains the following properties:
 
    name            - Data set descriptive name
    description     - Description of the data set
    userData        - Structure for holding additional related to the
                      data set
 
    observationInfo - Structure array holding additional
                      data per related to each observation
 
    nObservations     - Number of observations in the data set
    nTargetDimensions - Number of target dimensions
    isLabeled         - Whether or not the data set is labeled
 
  The prtDataSetBase class has the following methods
 
    getObservationNames - get the observation names
    setObservationNames - set the observation names
 
    getTargetNames      - get the target names
    setTargetNames      - set the target names
 
    getX - Shortcut for getObservations
    setX - Shortcut for setObservations
    getY - Shortcut for getTargets
    setY - Shortcut for setTargets
 
    setXY - Shortcut for setObservationsAndTargets
 
  The prtDataSetBase class also specifies the following abstract
  functions, which are implemented by all derived classes:
 
    getObservations - Return an array of observations
    setObservations - Set the array of observations
 
    getTargets - Return an array of targets (empty if unlabeled)
    setTargets - Set the array of targets
 
    setObservationsAndTargets - Set the array of observations and
                                targets
    catFeatures               - Combine the features from a data set
                                with another data set
    catObservations           - Combine the Observations from a data
                                set with another data set
    catTargets                - Combine the targets from a data set
                                with another data set
    removeObservations        - Remove observations from a data set
    retainObservations        - Retain observatons (remove all others)
                                from a data set
 
    removeTargets - Remove columns of targets from a data set
    retainTargets - Retain columns of targets from a data set
    plot          - Plot the data set
    summarize     - Output a summary of the data set