算法<十一>朴素贝叶斯分类算法

package com.example.demo.SortAlgorithm;
/*
 *
 * @Author: i_heh
 * @Date: 2019/7/5
 * @Time: 14:34
 * @Description: 朴素贝叶斯分类算法
 *
 */
import com.example.demo.SortAlgorithm.SortBean.JavaBean;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.ArrayList;

public class NaiveBayesian {

    /**data_length
     * 算法的思想
     */
    public static ArrayList<JavaBean> list = new ArrayList<JavaBean>();;
    static int data_length=0;
    public static void main(String[] args) {
        // 1.读取数据，放入list容器中
        File file = new File("E://test.txt");
        txt2String(file);
        //数据测试样本
        testData(25,"Medium","Yes","Fair");
    }
    // 读取样本数据
    public static void txt2String(File file) {

        try {
            BufferedReader br = new BufferedReader(new FileReader(file));// 构造一个BufferedReader类来读取文件
            String s = null;
            while ((s = br.readLine()) != null) {// 使用readLine方法，一次读一行
                data_length++;
                splitt(s);
            }
            br.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
    // 存入ArrayList中
    public static void splitt(String str){

        String strr = str.trim();
        String[] abc = strr.split("[\\p{Space}]+");
        int age=Integer.parseInt(abc[0]);
        JavaBean bean=new JavaBean(age, abc[1], abc[2], abc[3], abc[4]);
        list.add(bean);


    }
    // 训练样本，测试
    public static void testData(int age,String a,String b,String c){
        //训练样本
        int number_yes=0;
        int bumber_no=0;

        // age情况 个数
        int num_age_yes=0;
        int num_age_no=0;
        // income
        int num_income_yes=0;
        int num_income_no=0;
        // student
        int num_student_yes=0;
        int num_stdent_no=0;
        //credit
        int num_credit_yes=0;
        int num_credit_no=0;

        //遍历List 获得数据
        for(int i=0;i<list.size();i++){
            JavaBean bb=list.get(i);
            if(bb.getBuys_computer().equals("Yes")){ //Yes
                number_yes++;
                if(bb.getIncome().equals(a)){//income
                    num_income_yes++;
                }
                if(bb.getStudent().equals(b)){//student
                    num_student_yes++;
                }
                if(bb.getCredit_rating().equals(c)){//credit
                    num_credit_yes++;
                }
                if(bb.getAge()==age){//age
                    num_age_yes++;
                }


            }else {//No
                bumber_no++;
                if(bb.getIncome().equals(a)){//income
                    num_income_no++;
                }
                if(bb.getStudent().equals(b)){//student
                    num_stdent_no++;
                }
                if(bb.getCredit_rating().equals(c)){//credit
                    num_credit_no++;
                }
                if(bb.getAge()==age){//age
                    num_age_no++;
                }

            }
        }

        System.out.println("购买的历史个数:"+number_yes);
        System.out.println("不买的历史个数:"+bumber_no);

        System.out.println("购买+age:"+num_age_yes);
        System.out.println("不买+age:"+num_age_no);

        System.out.println("购买+income:"+num_income_yes);
        System.out.println("不买+income:"+num_income_no);

        System.out.println("购买+stundent:"+num_student_yes);
        System.out.println("不买+student:"+num_stdent_no);

        System.out.println("购买+credit:"+num_credit_yes);
        System.out.println("不买+credit:"+num_credit_no);
        //// 概率判断
        double buy_yes=number_yes*1.0/data_length; // 买的概率
        double buy_no=bumber_no*1.0/data_length; //  不买的概率
        System.out.println("训练数据中买的概率:"+buy_yes);
        System.out.println("训练数据中不买的概率:"+buy_no);
        /// 未知用户的判断
        double nb_buy_yes=(1.0*num_age_yes/number_yes)*(1.0*num_income_yes/number_yes)*(1.0*num_student_yes/number_yes)*(1.0*num_credit_yes/number_yes)*buy_yes;
        double nb_buy_no=(1.0*num_age_no/bumber_no)*(1.0*num_income_no/bumber_no)*(1.0*num_stdent_no/bumber_no)*(1.0*num_credit_no/bumber_no)*buy_no;
        System.out.println("新用户买的概率:"+nb_buy_yes);
        System.out.println("新用户不买的概率:"+nb_buy_no);
        if(nb_buy_yes>nb_buy_no){
            System.out.println("新用户买的概率大");
        }else {
            System.out.println("新用户不买的概率大");
        }
    }
}

package com.example.demo.SortAlgorithm.SortBean;


/*
 *
 * @Author: i_heh
 * @Date: 2019/7/5
 * @Time: 14:36
 * @Description:
 *
 */
public class JavaBean {
    int age;
    String income;
    String student;
    String credit_rating;
    String buys_computer;
    public JavaBean(){

    }
    public JavaBean(int age,String income,String student,String credit_rating,String buys_computer){
        this.age=age;
        this.income=income;
        this.student=student;
        this.credit_rating=credit_rating;
        this.buys_computer=buys_computer;
    }


    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getIncome() {
        return income;
    }
    public void setIncome(String income) {
        this.income = income;
    }
    public String getStudent() {
        return student;
    }
    public void setStudent(String student) {
        this.student = student;
    }
    public String getCredit_rating() {
        return credit_rating;
    }
    public void setCredit_rating(String credit_rating) {
        this.credit_rating = credit_rating;
    }
    public String getBuys_computer() {
        return buys_computer;
    }
    public void setBuys_computer(String buys_computer) {
        this.buys_computer = buys_computer;
    }

    @Override
    public String toString() {
        return "JavaBean [age=" + age + ", income=" + income + ", student="
                + student + ", credit_rating=" + credit_rating + ", buys_computer="
                + buys_computer + "]";
    }
}