programming-examples/java/To implement Na‹ve Bayesian Classifier.java

import java.util.*;
class btheo
{
    static char outlook[]= {'S','S','O','R','R','R','O','S','S','R','S','O','O','R'};
    static char temperature[]= {'H','H','H','M','C','C','C','M','C','M','M','M','H','M'};
    static char humidity[]= {'P','P','P','P','N','N','N','P','N','N','N','P','N','P'};
    static char windy[]= {'F','T','F','F','F','T','T','F','F','F','T','T','F','T'};
    static char class1[]= {'N','N','P','P','P','N','P','N','P','P','P','P','P','N'};
    static double prob[][]=new double[4][2];
    static double pp=9.0/14.0;
    static double npp=5.0/14.0;
    static int flag=0;
    static int flag1=0;
    static double play_N=1;
    static double notplay_N=1;
    static void cal_N(int a)
    {
        if(a==1)
            {
                for(int i=0; i<4; ++i)
                    play_N*=prob[i][0];
                play_N*=pp;
                //System.out.println("\nValue of N of play \n"+play_N);
            }
        Else
        {
            for(int i=0; i<4; ++i)
                notplay_N*=prob[i][1
                notplay_N*=npp;
                //System.out.println("\nValue of N of No play \n"+notplay_N);
            }
    }
    static double cal_play_prob(char ch)
    {
        double prob=0;
        double count=0;
        if(flag==0)
            {
                for(int i=0; i<14; ++i)
                    if(outlook[i]==ch && class1[i]=='P')
                        ++count;
                prob=count/9.0;
                flag=1;
            }
        else if
        (flag==1)
            {
                for(int i=0; i<14; ++i)
                    if(temperature[i]==ch && class1[i]=='P')
                        ++count;
                prob=count/9.0;
                flag=2;
            }
        else if
        (flag==2)
            {
                for(int i=0; i<14; ++i)
                    if(humidity[i]==ch && class1[i]=='P')
                        ++count;
                prob=count/9.0;
                flag=3;
            }
        else if(flag==3)
            {
                for(int i=0; i<14; ++i)
                    if(windy[i]==ch && class1[i]=='P')
                        ++count;
                prob=count/9.0;
            }
        return prob;
    }
    static double cal_noplay_prob(char ch)
    {
        double prob=0;
        double count=0;
        if(flag1==0)
            {
                for(int i=0; i<14; ++i)
                    if(outlook[i]==ch && class1[i]=='N')
                        ++count;
                prob=count/5.0;
                flag1=1;
            }
        else if(flag1==1)
            {
                for(int i=0; i<14; ++i)
                    if(temperature[i]==ch && class1[i]=='N')
                        ++count;
                prob=count/5.0;
                flag1=2;
            }
        else if(flag1==2)
            {
                for(int i=0; i<14; ++i)
                    if(humidity[i]==ch && class1[i]=='N')
                        ++count;
                prob=count/5.0;
                flag1=3;
            }
        else if(flag1==3)
            {
                for(int i=0; i<14; ++i)
                    if(windy[i]==ch && class1[i]=='N')
                        ++count;
                prob=count/5.0;
            }
        return prob;
    }
    public static void main(String args[])
    {
        Scanner scr=new Scanner(System.in);
        System.out.println("Table\n");
        System.out.println("Outlook\t   Temperature\t    Humidity\t      Windy     \tClass");
        for(int i=0; i<14; ++i)
            {
                System.out.print(outlook[i]+"\t\t"+temperature[i]+"\t\t"+humidity[i]+"\t\t"+windy[i]+"\t\t"+class1[i]);
                System.out.println();
            }
        System.out.println("Menu:\nOutlook: Sunny=S Overcast=O Rain=R\tTemperature: Hot=H Mild=M Cool=C\n");
        System.out.println("Humidity: Peak=P Normal=N\t\tWindy: True=T False=F\n\nYour input should belong to one of these classes.\n");
        System.out.println("class1: Play=P   class2:Not Play=NP");
        System.out.println("\nEnter your input: example. t={rain,hot,peak,false} input will be R,H,P,F");
        String s=scr.nextLine();
        char ch;
        int count=0;
        for(int i=0; i<8; i+=2)
            {
                ch=s.charAt(i);
                prob[count][0]=cal_play_prob(ch);
                prob[count][1]=cal_noplay_prob(ch);
                ++count;
            }
        cal_N(1);
        cal_N(2);
        double pt=play_N+notplay_N;
        double prob_of_play=0;
        double prob_of_noplay=0;
        prob_of_play=play_N/pt;
        prob_of_noplay=notplay_N/pt;
        System.out.println("\nProbability of play "+prob_of_play);
        System.out.println("\nProbability of NO play "+prob_of_noplay );
        if(prob_of_play>prob_of_noplay)
            System.out.println("\nThe new tuple classified under \"PLAY\" category.Hence there will be play!!!");
        else
            System.out.println("\nThe new tuple classified under \"NO PLAY\" category.Hence there will be NO play.");
    }
}
}