perfestimator.java

机器学习算法中的FSS算法

package fss;

import shared.*;
import shared.Error;
import java.lang.*;
import java.util.*;
import java.io.*;

/***************************************************************************
  PerfEstimator is an abstract base class for Performance Estimation 
methods.  Subclasses include CrossValidator (and StratifiedCV), as well as 
Bootstrap. Update PerfData to take into account the different sizes of 
folds by using weights in PerfData. dumpFiles should be made an option 
(very easy given the current layout).

@author James Louis	8/13/2001	Ported to Java
@author Dan Sommerfield	10/16/94	Minor function revisions.
@author Ronny Kohavi	9/12/94	Re-engineered Dan's project.
@author Dan Sommerfield	4/94	Initial revision (.h,.c) 
	(CS229B class project)	Based on Rich Long's CValidator.
***************************************************************************/

abstract public class PerfEstimator {

   protected String dumpStem = "";    // Don't dump if ""

   protected PerfData perfData;

   public static boolean warnedAlready = false; // moved here from train_and_test function -JL


/** A random number generator. **/
   private Random randNumGen = new Random();

/** Logging options for this class. **/
   protected LogOptions logOptions = new LogOptions();


/***************************************************************************
  This class has no access to a copy constructor.
***************************************************************************/
   private PerfEstimator(PerfEstimator source){}

/***************************************************************************
  Sets the logging level for this object.
@param level	The new logging level.
***************************************************************************/
   public void set_log_level(int level){logOptions.set_log_level(level);}

/***************************************************************************
  Returns the logging level for this object.
***************************************************************************/
   public int  get_log_level(){return logOptions.get_log_level();}

/***************************************************************************
  Sets the stream to which logging options are displayed.
@param strm	The stream to which logs will be written.
***************************************************************************/
   public void set_log_stream(Writer strm)
      {logOptions.set_log_stream(strm);}

/***************************************************************************
  Returns the stream to which logs for this object are written.
@return The stream to which logs for this object are written.
***************************************************************************/
   public Writer get_log_stream(){return logOptions.get_log_stream();}

/***************************************************************************
  Returns the LogOptions object for this object.
@return The LogOptions object for this object.
***************************************************************************/
   public LogOptions get_log_options(){return logOptions;}

/***************************************************************************
  Sets the LogOptions object for this object.
@param opt	The new LogOptions object.
***************************************************************************/
   public void set_log_options(LogOptions opt)
      {logOptions.set_log_options(opt);}

/***************************************************************************
  Sets the logging message prefix for this object.
@param file	The file name to be displayed in the prefix of log messages.
@param line	The line number to be displayed in the prefix of log messages.
@param lvl1 The log level of the statement being logged.
@param lvl2	The level of log messages being displayed.
***************************************************************************/
   public void set_log_prefixes(String file, int line,int lvl1, int lvl2)
      {logOptions.set_log_prefixes(file, line, lvl1, lvl2);}

/***************************************************************************
  Returns the random number generator for this object.
@return The random number generator for this object.
***************************************************************************/
   public Random rand_num_gen() {return randNumGen;}

/***************************************************************************
  Sets the seed for the random number generator stored in this object.
@param seed	The new seed for the number generator.
***************************************************************************/
   public void init_rand_num_gen(long seed) {randNumGen.setSeed(seed);}

/***************************************************************************
  Dump data to files if dumpStem != "" 
dumpSuffix is appended to dumpStem before .{names,data,test} are added.  
descr goes into the files as a comment.
@param
@param
@param
@param
***************************************************************************/
   protected void dump_data(String dumpSuffix, String descr,
         InstanceList trainList,
         InstanceList testList)
   {
      try{
         if (dumpStem != Globals.EMPTY_STRING)
         {
//obs      MLCOStream namesStream(dumpStem + dumpSuffix + Globals.DEFAULT_NAMES_EXT);
            FileWriter namesStream = new FileWriter(dumpStem + dumpSuffix + Globals.DEFAULT_NAMES_EXT);
            trainList.display_names(namesStream, true, descr);

//obs      MLCOStream trainStream(dumpStem + dumpSuffix + Globals.DEFAULT_DATA_EXT);
            FileWriter trainStream = new FileWriter(dumpStem + dumpSuffix + Globals.DEFAULT_DATA_EXT);
            trainStream.write("|"+descr+"\n"+trainList+"\n");

//obs      MLCOStream testStream(dumpStem + dumpSuffix + Globals.DEFAULT_TEST_EXT);
            FileWriter testStream = new FileWriter(dumpStem + dumpSuffix + Globals.DEFAULT_TEST_EXT);
            testStream.write("|"+descr+"\n"+testList+"\n");
         }
      }catch(IOException e){e.printStackTrace(); System.exit(1);}
   }   

   // NULL value for localErrorData means don't update error.
   //   virtual void update_acc_data(int numCorrect, int numIncorrect,
   //				ErrorData *localErrorData);

   // show how stratified this particular train/test pair are
/***************************************************************************
  Shows how stratified a hold out is.
@param
@param
***************************************************************************/
protected void show_stratification(InstanceList trainPart,
				       InstanceList testPart)
{
   logOptions.LOG(2, "Stratification: Training: ");
//obs   InstanceListArray *trainBPA = trainPart.split_by_label();
//obs   for(int i=trainBPA->low(); i<=trainBPA->high(); i++)
//obs      logOptions.LOG(2, (*trainBPA)[i]->num_instances() << "/");
   InstanceList[] trainBPA = trainPart.split_by_label();
   for(int i=0; i<trainBPA.length; i++)
      logOptions.LOG(2, (trainBPA)[i].num_instances() +"/");
   trainBPA = null;

   logOptions.LOG(2, "  Test: ");
//obs   InstanceListArray *testBPA = testPart.split_by_label();
//obs   for(i=testBPA->low(); i<=testBPA->high(); i++)
//obs      logOptions.LOG(2, (*testBPA)[i]->num_instances() << "/");
   InstanceList[] testBPA = testPart.split_by_label();
   for(int i=0; i<testBPA.length; i++)
      logOptions.LOG(2, (testBPA)[i].num_instances() +"/");
   testBPA = null;

   logOptions.LOG(2, "\n");
}





   
   // train_and_test should call dump_data
   // This is protected so we can test outside programs like C4.5
/***************************************************************************
  Trains and tests the given inducer using the given test set, and the 
trainList member. Fills in the perfData array. The complexity of is that 
inducer.train() + CatTestResult(). We could almost get away with a 
DumpInducer which simply dumps the data it gets, and then appends to a test 
file the instances it gets to categorize.  The problem is that when 
categorizing, the instances are unlabelled. If localPerfData is NULL, we 
don't update any statistics, but we still return the error
@return
@param
@param
@param
@param
@param
***************************************************************************/
protected double train_and_test(BaseInducer inducer,
				  InstanceList trainList, 
 			        InstanceList testList,
				  String dumpSuffix,
				  PerfData localPerfData)
{
   // show stratification at loglevel 3
//obs   IFLOG(3, show_stratification(trainList, testList));
   if(get_log_level() >= 3) show_stratification(trainList, testList);

   // dump before assign_data, because we'll lose ownership.
   dump_data(dumpSuffix, description(), trainList, testList);

   double error = 0.0;
   
   if (localPerfData == null || !inducer.can_cast_to_inducer()) {
      if(inducer.supports_full_testing()) {
	 CatTestResult result = inducer.train_and_perf(trainList, testList);
	 error = result.error();
	 if(localPerfData != null)
	    localPerfData.insert(result);
	 result = null;
      }
      else {
	 error = inducer.train_and_test(trainList, testList);
	 if (localPerfData != null)
	    localPerfData.insert_error(error);	
      }
   }
   else {
      CatTestResult result = inducer.train_and_perf(trainList, testList);
      error = result.error();
      localPerfData.insert(result);
      result = null;
   }

   double totalWeight = testList.total_weight();
   double weightIncorrect = error * totalWeight;

   // Nice test, but doesn't work when the inner inducer is a
   // Performance estimator itself.  Therefore, this is a warning.
   if (!warnedAlready && 
       Math.abs(weightIncorrect / totalWeight - error) > 0.001) {
       try{
         Globals.Mcerr.write("PerfEstimator::train_and_test: suspicious error "
            +error+" does not divide well total weight of instances "
            +totalWeight +" (" +(weightIncorrect / totalWeight)
            +" vs. "+error+".  This is OK for PerfEstInducer."
            +" Further warnings of this type suppressed.\n");
       }catch(IOException e){e.printStackTrace(); System.exit(1);}
       warnedAlready = true;
   }

   return error;
}



/***************************************************************************
  Basic constructor.
***************************************************************************/
public PerfEstimator()
{ perfData = null;}

/***************************************************************************