源代码id3java的简单介绍

求助含有Junit测试代码的Java源代码，用来学习Junit

下面是我做项目时的例子，希望对你有所帮助。

/*

*@author ougaoyan ,date:2008-10-19

*/

package test;

import java.util.Date;

import junit.framework.TestCase;

import app.DA.BookDA;

import app.PD.Book;

public class TestBookDA extends TestCase {

public TestBookDA(String name){

super(name);

}

// public Book(int bookID, String cip, String name, String author,String press, String category, int quantity, int reborrowable,int borrowerID,Date startDate)

public void testEditBook(){

Book book1 = new Book(1,"123456","信号","张建","某出版社","电信",1,1,1,new Date());

Book book2 = new Book(-1,"123456","信号","张建","某出版社","电信",1,1,1,new Date());

Book book3 = new Book(99,"123456","信号","张建","某出版社","电信",1,1,1,new Date());

Book book4 = new Book(1,"123456","信号","张建","某出版社","电信",1,1,1,new Date());

assertEquals(true,BookDA.editBook(book1));

assertEquals(false,BookDA.editBook(book2));

assertEquals(true,BookDA.editBook(book3));

assertEquals(false,BookDA.editBook(book4));

}

////Book(int borrowerID, Date startDate, int reBorrowable, String cip)

public void testAddBook(){

Book book1 = new Book(0,"234567","信发号","张建","某出版社","电信",1,1,1,new Date());

Book book2 = new Book(0,"123456","信的号","张建","某出版社","电信",1,1,1,new Date());

Book book3 = new Book(0,"99999","信i号","张建","某出版社","电信",1,1,1,new Date());

assertEquals(true,BookDA.addBook(book1));

assertEquals(true,BookDA.addBook(book2));

assertEquals(false,BookDA.addBook(book3));

}

public static void main(String[] args) {

junit.textui.TestRunner.run(TestBookDA.class);

System.out.println(new TestBookDA("TestBookDA").countTestCases());

}

}

/*

*@author ougaoyan ,date:2008-10-19

*/

package test;

import java.util.Date;

import java.util.Vector;

import junit.framework.TestCase;

import app.DA.CipDA;

import app.PD.Cip;

public class TestCipDA extends TestCase {

public TestCipDA (String name){

super(name);

}

public void testFindBooksByName(){

String name1 = "数据库";

String name2 = "小小";

Vector vector1 = CipDA.findBooksByName(name1);

Vector vector2 = CipDA.findBooksByName(name2);

assertNotNull(vector1);

assertNull(vector2);

}

public void testFindBooksByAuthor(){

String name1 = "欧阳";

String name2 = "小小";

Vector vector1 = CipDA.findBooksByAuthor(name1);

Vector vector2 = CipDA.findBooksByAuthor(name2);

assertNotNull(vector1);

assertNull(vector2);

}

public void testFindBooksByCategory(){

String name1 = "计算机";

String name2 = "计 算 机";

String name3 = "wucimin";

Vector vector1 = CipDA.findBooksByCategory(name1);

Vector vector2 = CipDA.findBooksByCategory(name2);

Vector vector3 = CipDA.findBooksByCategory(name3);

assertNotNull(vector1);

assertNotNull(vector2);

assertNull(vector3);

}

// public void testEditCip(){

// }

//public Cip(String cip, String name, String author, String press,String category, int quantity, int reserverID,Date reservedDate)

public void testAddCip(){

Cip cip1 = new Cip("2244","新加书","新者","出版社","计算机",3,0,new Date());

//Cip cip2 =new Cip(null,"新加书","新者","出版社","计算机",3,0,new Date());

Cip cip3 =new Cip("22er3rr3rt4t43t43t3t34t34t34t44","新加书","新者","出版社","计算机",3,0,new Date());

assertEquals(true,CipDA.addCip(cip1));

//assertEquals(false,CipDA.addCip(cip2));

assertEquals(false,CipDA.addCip(cip3));

}

public void testEditCip(){

Cip cip1 = new Cip("2244","新加书","新者","出版社","计算机",3,0,new Date());

Cip cip2 =new Cip(null,"新加书","新者","出版社","计算机",3,0,new Date());

Cip cip3 =new Cip("22er3rr3rt4t43t43t3t34t34t34t44","新加书","新者","出版社","计算机",3,0,new Date());

assertEquals(true,CipDA.editCip(cip1));

assertEquals(false,CipDA.editCip(cip2));

assertEquals(false,CipDA.editCip(cip3));

}

public static void main(String[] args) {

junit.textui.TestRunner.run(TestCipDA.class);

System.out.println(new TestCipDA("TestCipDA").countTestCases());

}

}

/*

*@author ougaoyan ,date:2008-10-19

*/

package test;

import java.util.Date;

import java.util.Vector;

import junit.framework.TestCase;

import app.DA.LibManagerDA;

import app.PD.LibManager;

import app.PD.Student;

public class TestLibManagerDA extends TestCase {

public TestLibManagerDA(String name){

super(name);

}

public void testCheck(){

String userName1 = "1234";

String password1 = "111111";

String userName2 = "";

String password2= "";

String userName3 = "1234";

String password3 = "111";

LibManager libmanager = new LibManager(1,userName1,password1,"w");

assertEquals(libmanager.getID(), LibManagerDA.check(userName1,password1).getID());

assertEquals(libmanager.getName(), LibManagerDA.check(userName1,password1).getName());

assertEquals(null, LibManagerDA.check(userName2,password2));

assertEquals(null, LibManagerDA.check(userName3,password3));

}

public void testUpdatePwd(){

int id1 =1,id2=99;

String qpwd="234567";

assertEquals(true,LibManagerDA.updatePwd(id1, qpwd));

assertEquals(false,LibManagerDA.updatePwd(id2, qpwd));

}

public void testSearchLibManager(){

LibManager libmanager1 = new LibManager(1,"1234","111111","w");

LibManager libmanager2 = new LibManager(2,"2345","23456","x");

assertEquals(libmanager1.getID(), LibManagerDA.searchLibManager("1234").getID());

assertEquals(libmanager2.getID(), LibManagerDA.searchLibManager("2345").getID());

assertNull(LibManagerDA.searchLibManager(""));

}

public void testQuantity(){

String cip1 = "123456";

String cip2 = "234567";

assertEquals(1,LibManagerDA.getBookQuantity(cip1));

assertEquals(3,LibManagerDA.getBookQuantity(cip2));

assertEquals(-1,LibManagerDA.getBookQuantity(""));

}

public void testEditLibManager(){

LibManager libmanager1 = new LibManager(1,"1234","111111","w");

LibManager libmanager2 = new LibManager(2,"2345","23456","x");

//LibManager libmanager3 = new LibManager(90,"123456677","0","y");

LibManager libmanager4 = new LibManager(3,"123456677","0","e");

assertEquals(true, LibManagerDA.editLibManager(libmanager1));

assertEquals(true,LibManagerDA.editLibManager(libmanager2));

//assertEquals(false,LibManagerDA.editLibManager(libmanager3));

assertEquals(false,LibManagerDA.editLibManager(libmanager4));

}

public void testAddLibManager(){

LibManager libmanager1 = new LibManager(-1,"1234","0","z");

LibManager libmanager2 = new LibManager(-1,"2345","0","x");

LibManager libmanager3 = new LibManager(-1,"12hh3456677","0","y");

assertEquals(true, LibManagerDA.addLibManager(libmanager1));

assertEquals(true,LibManagerDA.addLibManager(libmanager2));

assertEquals(false,LibManagerDA.addLibManager(libmanager3));

}

public void testGetBookCip(){

int bookid1 =1;

int bookid2 =4;

int bookid3 = -1;

String exceptedcip1 = "123456";

String exceptedcip2="234567";

String exceptedcip3 = null;

assertEquals(exceptedcip1, LibManagerDA.getBookCip(bookid1));

assertEquals(exceptedcip2, LibManagerDA.getBookCip(bookid2));

assertEquals(exceptedcip3, LibManagerDA.getBookCip(bookid3));

}

public void testCheckReserved(){

String cip1 = "123456";

String cip2 = "234567";

int studentid1 = 1;

int studentid2 = 2;

int studentid3 = 99;

assertEquals(true, LibManagerDA.checkReserved(cip1,studentid1));

assertEquals(true, LibManagerDA.checkReserved(cip2,studentid2));

assertEquals(false, LibManagerDA.checkReserved(cip1,studentid2));

assertEquals(false,LibManagerDA.checkReserved(cip2,studentid1));

assertEquals(false,LibManagerDA.checkReserved(cip2,studentid3));

assertEquals(false,LibManagerDA.checkReserved(cip1,studentid3));

}

//public static boolean borrowOPeration(int quantity, int bookID, int borrowerID,int reservedNum, int borrowedNum,Date startDate)

public void testBorrowOPeration(){

int quantity1 = 1;

int bookID1 = 2;

int borrowerID1 = 3;

int reservedNum1 = 1;

int borrowedNum1 = 4;

int quantity2 = 1;

int bookID2 = 1;

int borrowerID2 = 3;

int reservedNum2 = 0;

int borrowedNum2 = 7;

assertEquals(true,LibManagerDA.borrowOperation(quantity1, bookID1, borrowerID1, reservedNum1, borrowedNum1, new Date()));

assertEquals(false,LibManagerDA.borrowOperation(quantity2, bookID2, borrowerID2, reservedNum2, borrowedNum2, new Date()));

}

//public static boolean returnOperation (int quantity, int bookID, int borrowerID, int borrowedNum, Date startDate, int reborrowable)

public void testReturnOperation(){

int quantity1 = 1;

int bookID1 = 1;

int borrowerID1 = 1;

int borrowedNum1 = 4;

int reborrowable1 = 0;

int quantity2 = 1;

int bookID2 = 2;

int borrowerID2 = 2;

int borrowedNum2 = 7;

int reborrowable2 = 0;

assertEquals(true,LibManagerDA.returnOperation(quantity1, bookID1, borrowerID1, borrowedNum1, new Date(),reborrowable1));

assertEquals(true,LibManagerDA.returnOperation(quantity2, bookID2, borrowerID2, borrowedNum2,new Date(), reborrowable2));

}

public void testGetBookQuantity(){

String cip1 = "123456";

String cip2 = "234567";

int quantity1 = 5;

int quantity2 = 3;

assertEquals(quantity1,LibManagerDA.getBookQuantity(cip1));

assertEquals(quantity2,LibManagerDA.getBookQuantity(cip2));

}

public void testFindBill(){

String userName1 = "111111";

String userName2 = "222222";

float bill1 = 0;

float bill2 = 0;

assertEquals(bill1,LibManagerDA.findBill(userName1),0.000001);

assertEquals(bill2,LibManagerDA.findBill(userName2),0.000001);

}

public void testClearBill(){

String userName1 = "111111";

String userName2 = "222222";

assertEquals(true,LibManagerDA.clearBill(userName1));

assertEquals(true,LibManagerDA.clearBill(userName2));

}

public void testSelectAllLibManager(){

Vector allLibManager = new Vector();

allLibManager = LibManagerDA.selectAllLibManager();

for(int i = 0;i allLibManager.size();i++ ){

LibManager libManager = (LibManager)allLibManager.get(i);

System.out.println(libManager.getName());

}

}

public void testSecelctAllStudent(){

Vector allStudent = new Vector();

allStudent = LibManagerDA.secelctAllStudent();

for(int i = 0;i allStudent.size();i++ ){

Student student = (Student)allStudent.get(i);

System.out.println(student.getName());

}

}

public void testStartTimes(){

Vector times = new Vector();

times = LibManagerDA.startTimes(0);

for(int i = 0;i times.size();i ++)

System.out.println((Date)times.get(i));

}

public void testUpdateStuBill() {

}

public static void main(String[] args) {

junit.textui.TestRunner.run(TestLibManagerDA.class);

System.out.println(new TestLibManagerDA("dd ").countTestCases());

}

}

/*

*@author ougaoyan ,date:2008-10-19

*/

package test;

import java.util.Date;

import java.util.Vector;

import junit.framework.TestCase;

import app.DA.StudentDA;

import app.PD.Book;

import app.PD.Cip;

import app.PD.Student;

public class TestStudentDA extends TestCase {

public TestStudentDA(String name){

super(name);

}

/*public Student(int id, int borrowedNum, int reservedNum, float bill,

String userName, String password, String name, String department,

String unit, String sex) */

public void testCheck(){

Student student1 = new Student(1,0,0,0,"111111","123456","张三","软件","0602","男");

//Student student2 = new Student(1,0,0,0,"111111","123","张三","软件","0602","男");

//Student student3 = new Student(2,0,0,0,"11111","123456","张三","软件","0602","男");

assertEquals(student1.getId(),StudentDA.check("111111","123456").getId());

assertEquals(true,student1.getId()==StudentDA.check("111111","123456").getId());

assertEquals(null,StudentDA.check("111111","12356"));

//assertEquals(false,);

//assertEquals(false,);

}

public void testUpdatePwd(){

int id1 = 1;

int id2 = 2;

int id3 = -1;

String password1 = "123456";

String password2 = "234567";

String password3 = "1234555";

assertEquals(true,StudentDA.updatePwd(id1, password1));

assertEquals(true,StudentDA.updatePwd(id2, password2));

assertEquals(false,StudentDA.updatePwd(id3, password3));

}

public void testSearchStudent(){

Student student1 = new Student(1,0,0,0,"111111","123456","张三","软件","0602","男");

assertEquals(true,student1.getId()==StudentDA.searchStudent("111111").getId());

assertEquals(null,StudentDA.searchStudent("111"));

}

public void testEditStudent(){

Student student1 = new Student(1,0,0,0,"111111","123456","张三","软件","0602","女");

Student student2 = new Student(1,0,0,0,"11111333555555555556631","123456","张三","软件","0602","女");

assertEquals(true,StudentDA.editStudent(student1));

assertEquals(false,StudentDA.editStudent(student2));

}

public void testAddStudent(){

Student student1 = new Student(5,0,0,0,"111111","123456","张三","软件","0602","女");

Student student2 = new Student(1,0,0,0,"1111133331","123456","张三","软件","0602","女");

assertEquals(true,StudentDA.addStudent(student1));

//assertEquals(false,StudentDA.addStudent(student2));

}

public static void testGetBorrowBookInfor(){

int studentid1 = 1;

int studentid2 = 2;

int studentid3 = 5;

Vector vector1 = new Vector();

Vector vector2 = new Vector();

Vector vector3 = new Vector();

vector1 = StudentDA.getBorrowBookInfor(studentid1);

vector2 = StudentDA.getBorrowBookInfor(studentid2);

vector3 = StudentDA.getBorrowBookInfor(studentid3);

//System.out.println(vector1);

assertNotNull(((Book)vector1.get(0)).getName());

}

public void testGetReserveBookInfor(){

int studentid1 = 1;

Vector vector1 = new Vector();

vector1 = StudentDA.getReserveBookInfor(studentid1);

assertEquals("数据库",((Cip)vector1.get(0)).getCategory());

}

//public static boolean reserveOperation(int reserverID1, String cip1, int quantity1, int reservedNum1, Date reservedDate1 )

public void testReserveOperation(){

assertEquals(true,StudentDA.reserveOperation(1, "123456", 1, 2, new Date()));

}

//void cancelReservation(int reserverID1,String cip1, int quantity1, int reserveNum1)

public void testCancelReservation(){

assertTrue(StudentDA.cancelReservation(1, "1234567", 1, 3));

}

//public static boolean updateReborrowable(int bookID, int reborrowable1, int studentID,Date startDate1)

public void testUpdateReborrowable(){

assertTrue(StudentDA.updateReborrowable(2,0,1,new Date()));

}

public static void main(String[] args) {

//junit.textui.TestRunner.run(TestStudentDA.class);

//System.out.println(new TestStudentDA("TestStudentDA").countTestCases());

testGetBorrowBookInfor();

}

}

/*

*@author ougaoyan ,date:2008-10-19

*/

package test;

import junit.framework.Test;

import junit.framework.TestSuite;

public class AllTests {

public static Test suite() {

TestSuite suite = new TestSuite("Test for test");

suite.addTestSuite(TestLibManagerDA.class);

suite.addTestSuite(TestBookDA.class);

suite.addTestSuite(TestCipDA.class);

suite.addTestSuite(TestStudentDA.class);

//suite.addTestSuite(TestLibManagerDA.class);

//$JUnit-END$

return suite;

}

}

相关问答

Q1: 求助 weka 的ID3算法java源码

/*

* This program is free software; you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation; either version 2 of the License, or

* (at your option) any later version.

*

* This program is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU General Public License

* along with this program; if not, write to the Free Software

* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

/*

* Id3.java

* Copyright (C) 1999 University of Waikato, Hamilton, New Zealand

*

*/

package weka.classifiers.trees;

import weka.classifiers.Classifier;

import weka.classifiers.Sourcable;

import weka.core.Attribute;

import weka.core.Capabilities;

import weka.core.Instance;

import weka.core.Instances;

import weka.core.NoSupportForMissingValuesException;

import weka.core.RevisionUtils;

import weka.core.TechnicalInformation;

import weka.core.TechnicalInformationHandler;

import weka.core.Utils;

import weka.core.Capabilities.Capability;

import weka.core.TechnicalInformation.Field;

import weka.core.TechnicalInformation.Type;

import java.util.Enumeration;

/**

!-- globalinfo-start --

* Class for constructing an unpruned decision tree based on the ID3 algorithm. Can only deal with nominal attributes. No missing values allowed. Empty leaves may result in unclassified instances. For more information see: br/

* br/

* R. Quinlan (1986). Induction of decision trees. Machine Learning. 1(1):81-106.

* p/

!-- globalinfo-end --

*

!-- technical-bibtex-start --

* BibTeX:

* pre

* #64;article{Quinlan1986,

* author = {R. Quinlan},

* journal = {Machine Learning},

* number = {1},

* pages = {81-106},

* title = {Induction of decision trees},

* volume = {1},

* year = {1986}

* }

* /pre

* p/

!-- technical-bibtex-end --

*

!-- options-start --

* Valid options are: p/

*

* pre -D

* If set, classifier is run in debug mode and

* may output additional info to the console/pre

*

!-- options-end --

*

* @author Eibe Frank (eibe@cs.waikato.ac.nz)

* @version $Revision: 6404 $

*/

public class Id3

extends Classifier

implements TechnicalInformationHandler, Sourcable {

/** for serialization */

static final long serialVersionUID = -2693678647096322561L;

/** The node's successors. */

private Id3[] m_Successors;

/** Attribute used for splitting. */

private Attribute m_Attribute;

/** Class value if node is leaf. */

private double m_ClassValue;

/** Class distribution if node is leaf. */

private double[] m_Distribution;

/** Class attribute of dataset. */

private Attribute m_ClassAttribute;

/**

* Returns a string describing the classifier.

* @return a description suitable for the GUI.

*/

public String globalInfo() {

return "Class for constructing an unpruned decision tree based on the ID3 "

+ "algorithm. Can only deal with nominal attributes. No missing values "

+ "allowed. Empty leaves may result in unclassified instances. For more "

+ "information see: \n\n"

+ getTechnicalInformation().toString();

}

/**

* Returns an instance of a TechnicalInformation object, containing

* detailed information about the technical background of this class,

* e.g., paper reference or book this class is based on.

*

* @return the technical information about this class

*/

public TechnicalInformation getTechnicalInformation() {

TechnicalInformation result;

result = new TechnicalInformation(Type.ARTICLE);

result.setValue(Field.AUTHOR, "R. Quinlan");

result.setValue(Field.YEAR, "1986");

result.setValue(Field.TITLE, "Induction of decision trees");

result.setValue(Field.JOURNAL, "Machine Learning");

result.setValue(Field.VOLUME, "1");

result.setValue(Field.NUMBER, "1");

result.setValue(Field.PAGES, "81-106");

return result;

}

/**

* Returns default capabilities of the classifier.

*

* @return the capabilities of this classifier

*/

public Capabilities getCapabilities() {

Capabilities result = super.getCapabilities();

result.disableAll();

// attributes

result.enable(Capability.NOMINAL_ATTRIBUTES);

// class

result.enable(Capability.NOMINAL_CLASS);

result.enable(Capability.MISSING_CLASS_VALUES);

// instances

result.setMinimumNumberInstances(0);

return result;

}

/**

* Builds Id3 decision tree classifier.

*

* @param data the training data

* @exception Exception if classifier can't be built successfully

*/

public void buildClassifier(Instances data) throws Exception {

// can classifier handle the data?

getCapabilities().testWithFail(data);

// remove instances with missing class

data = new Instances(data);

data.deleteWithMissingClass();

makeTree(data);

}

/**

* Method for building an Id3 tree.

*

* @param data the training data

* @exception Exception if decision tree can't be built successfully

*/

private void makeTree(Instances data) throws Exception {

// Check if no instances have reached this node.

if (data.numInstances() == 0) {

m_Attribute = null;

m_ClassValue = Instance.missingValue();

m_Distribution = new double[data.numClasses()];

return;

}

// Compute attribute with maximum information gain.

double[] infoGains = new double[data.numAttributes()];

Enumeration attEnum = data.enumerateAttributes();

while (attEnum.hasMoreElements()) {

Attribute att = (Attribute) attEnum.nextElement();

infoGains[att.index()] = computeInfoGain(data, att);

}

m_Attribute = data.attribute(Utils.maxIndex(infoGains));

// Make leaf if information gain is zero.

// Otherwise create successors.

if (Utils.eq(infoGains[m_Attribute.index()], 0)) {

m_Attribute = null;

m_Distribution = new double[data.numClasses()];

Enumeration instEnum = data.enumerateInstances();

while (instEnum.hasMoreElements()) {

Instance inst = (Instance) instEnum.nextElement();

m_Distribution[(int) inst.classValue()]++;

}

Utils.normalize(m_Distribution);

m_ClassValue = Utils.maxIndex(m_Distribution);

m_ClassAttribute = data.classAttribute();

} else {

Instances[] splitData = splitData(data, m_Attribute);

m_Successors = new Id3[m_Attribute.numValues()];

for (int j = 0; j m_Attribute.numValues(); j++) {

m_Successors[j] = new Id3();

m_Successors[j].makeTree(splitData[j]);

}

}

}

/**

* Classifies a given test instance using the decision tree.

*

* @param instance the instance to be classified

* @return the classification

* @throws NoSupportForMissingValuesException if instance has missing values

*/

public double classifyInstance(Instance instance)

throws NoSupportForMissingValuesException {

if (instance.hasMissingValue()) {

throw new NoSupportForMissingValuesException("Id3: no missing values, "

+ "please.");

}

if (m_Attribute == null) {

return m_ClassValue;

} else {

return m_Successors[(int) instance.value(m_Attribute)].

classifyInstance(instance);

}

}

/**

* Computes class distribution for instance using decision tree.

*

* @param instance the instance for which distribution is to be computed

* @return the class distribution for the given instance

* @throws NoSupportForMissingValuesException if instance has missing values

*/

public double[] distributionForInstance(Instance instance)

throws NoSupportForMissingValuesException {

if (instance.hasMissingValue()) {

throw new NoSupportForMissingValuesException("Id3: no missing values, "

+ "please.");

}

if (m_Attribute == null) {

return m_Distribution;

} else {

return m_Successors[(int) instance.value(m_Attribute)].

distributionForInstance(instance);

}

}

/**

* Prints the decision tree using the private toString method from below.

*

* @return a textual description of the classifier

*/

public String toString() {

if ((m_Distribution == null) (m_Successors == null)) {

return "Id3: No model built yet.";

}

return "Id3\n\n" + toString(0);

}

/**

* Computes information gain for an attribute.

*

* @param data the data for which info gain is to be computed

* @param att the attribute

* @return the information gain for the given attribute and data

* @throws Exception if computation fails

*/

private double computeInfoGain(Instances data, Attribute att)

throws Exception {

double infoGain = computeEntropy(data);

Instances[] splitData = splitData(data, att);

for (int j = 0; j att.numValues(); j++) {

if (splitData[j].numInstances() 0) {

infoGain -= ((double) splitData[j].numInstances() /

(double) data.numInstances()) *

computeEntropy(splitData[j]);

}

}

return infoGain;

}

/**

* Computes the entropy of a dataset.

*

* @param data the data for which entropy is to be computed

* @return the entropy of the data's class distribution

* @throws Exception if computation fails

*/

private double computeEntropy(Instances data) throws Exception {

double [] classCounts = new double[data.numClasses()];

Enumeration instEnum = data.enumerateInstances();

while (instEnum.hasMoreElements()) {

Instance inst = (Instance) instEnum.nextElement();

classCounts[(int) inst.classValue()]++;

}

double entropy = 0;

for (int j = 0; j data.numClasses(); j++) {

if (classCounts[j] 0) {

entropy -= classCounts[j] * Utils.log2(classCounts[j]);

}

}

entropy /= (double) data.numInstances();

return entropy + Utils.log2(data.numInstances());

}

/**

* Splits a dataset according to the values of a nominal attribute.

*

* @param data the data which is to be split

* @param att the attribute to be used for splitting

* @return the sets of instances produced by the split

*/

private Instances[] splitData(Instances data, Attribute att) {

Instances[] splitData = new Instances[att.numValues()];

for (int j = 0; j att.numValues(); j++) {

splitData[j] = new Instances(data, data.numInstances());

}

Enumeration instEnum = data.enumerateInstances();

while (instEnum.hasMoreElements()) {

Instance inst = (Instance) instEnum.nextElement();

splitData[(int) inst.value(att)].add(inst);

}

for (int i = 0; i splitData.length; i++) {

splitData[i].compactify();

}

return splitData;

}

/**

* Outputs a tree at a certain level.

*

* @param level the level at which the tree is to be printed

* @return the tree as string at the given level

*/

private String toString(int level) {

StringBuffer text = new StringBuffer();

if (m_Attribute == null) {

if (Instance.isMissingValue(m_ClassValue)) {

text.append(": null");

} else {

text.append(": " + m_ClassAttribute.value((int) m_ClassValue));

}

} else {

for (int j = 0; j m_Attribute.numValues(); j++) {

text.append("\n");

for (int i = 0; i level; i++) {

text.append("| ");

}

text.append(m_Attribute.name() + " = " + m_Attribute.value(j));

text.append(m_Successors[j].toString(level + 1));

}

}

return text.toString();

}

/**

* Adds this tree recursively to the buffer.

*

* @param id the unqiue id for the method

* @param buffer the buffer to add the source code to

* @return the last ID being used

* @throws Exception if something goes wrong

*/

protected int toSource(int id, StringBuffer buffer) throws Exception {

int result;

int i;

int newID;

StringBuffer[] subBuffers;

buffer.append("\n");

buffer.append(" protected static double node" + id + "(Object[] i) {\n");

// leaf?

if (m_Attribute == null) {

result = id;

if (Double.isNaN(m_ClassValue)) {

buffer.append(" return Double.NaN;");

} else {

buffer.append(" return " + m_ClassValue + ";");

}

if (m_ClassAttribute != null) {

buffer.append(" // " + m_ClassAttribute.value((int) m_ClassValue));

}

buffer.append("\n");

buffer.append(" }\n");

} else {

buffer.append(" checkMissing(i, " + m_Attribute.index() + ");\n\n");

buffer.append(" // " + m_Attribute.name() + "\n");

// subtree calls

subBuffers = new StringBuffer[m_Attribute.numValues()];

newID = id;

for (i = 0; i m_Attribute.numValues(); i++) {

newID++;

buffer.append(" ");

if (i 0) {

buffer.append("else ");

}

buffer.append("if (((String) i[" + m_Attribute.index()

+ "]).equals(\"" + m_Attribute.value(i) + "\"))\n");

buffer.append(" return node" + newID + "(i);\n");

subBuffers[i] = new StringBuffer();

newID = m_Successors[i].toSource(newID, subBuffers[i]);

}

buffer.append(" else\n");

buffer.append(" throw new IllegalArgumentException(\"Value '\" + i["

+ m_Attribute.index() + "] + \"' is not allowed!\");\n");

buffer.append(" }\n");

// output subtree code

for (i = 0; i m_Attribute.numValues(); i++) {

buffer.append(subBuffers[i].toString());

}

subBuffers = null;

result = newID;

}

return result;

}

/**

* Returns a string that describes the classifier as source. The

* classifier will be contained in a class with the given name (there may

* be auxiliary classes),

* and will contain a method with the signature:

* precode

* public static double classify(Object[] i);

* /code/pre

* where the array codei/code contains elements that are either

* Double, String, with missing values represented as null. The generated

* code is public domain and comes with no warranty. br/

* Note: works only if class attribute is the last attribute in the dataset.

*

* @param className the name that should be given to the source class.

* @return the object source described by a string

* @throws Exception if the source can't be computed

*/

public String toSource(String className) throws Exception {

StringBuffer result;

int id;

result = new StringBuffer();

result.append("class " + className + " {\n");

result.append(" private static void checkMissing(Object[] i, int index) {\n");

result.append(" if (i[index] == null)\n");

result.append(" throw new IllegalArgumentException(\"Null values "

+ "are not allowed!\");\n");

result.append(" }\n\n");

result.append(" public static double classify(Object[] i) {\n");

id = 0;

result.append(" return node" + id + "(i);\n");

result.append(" }\n");

toSource(id, result);

result.append("}\n");

return result.toString();

}

/**

* Returns the revision string.

*

* @return the revision

*/

public String getRevision() {

return RevisionUtils.extract("$Revision: 6404 $");

}

/**

* Main method.

*

* @param args the options for the classifier

*/

public static void main(String[] args) {

runClassifier(new Id3(), args);

}

}

Q2: 无法删除数据库里的记录，character varying是对应java里的String类型的吗？

删除teacher表里面源代码id3java的teacherID为'id3',是否teacherID为'id3'在其它的表里面也出现了源代码id3java，是否执行语句后处于不一致状态，这就是事务的概念了。

数据库没有任何改变String sql="DELETE FROM teacher WHERE teacheID='id3'";

其中teacheID 应为teacherID吧

源代码id3java的介绍就聊到这里吧，感谢你花时间阅读本站内容，更多关于、源代码id3java的信息别忘了在本站进行查找喔。