myapriori.java

java实现apriori算法的一个实例

import java.util.*;

public class myapriori{
    double minsup=0.6;//最小支持度
    double minconf=0.8;//最小置信度
    int item_counts=0;//候选1项目集大小,即字母的个数
    int frequent_top;
    HashMap rule=new HashMap();
    String trans_set[]={"MONKEY","DONKEY","MAKE","MUCKY","COOKIE"};//事务集
    TreeSet[] frequent_set=new TreeSet[30];//频繁项集数组，[0]:代表1频繁集...
    TreeSet max_frequent=new TreeSet();//最大频繁集
    TreeSet item1_canditate=new TreeSet();//1候选集
    TreeSet canditate_set[]=new TreeSet[30];//候选集数组    
    
    public myapriori(){
        max_frequent=new TreeSet();
        item_counts=counts();
        //frequent_set[]=new TreeSet[3];
        //frequent_set[]=new TreeSet[item_counts];
        for(int i=0;i<item_counts;i++){    
            frequent_set[i]=new TreeSet();
            canditate_set[i]=new TreeSet();
        }
        //System.out.println(frequent_set[0].size());
        canditate_set[0]=item1_canditate;
    }
    
    //计算1候选集个数
    int counts(){
                String temp1=new String("a");
                char temp2='a';
                int i,j,m;
                for(i=0;i<trans_set.length;i++){
                        temp1=trans_set[i];
                        //System.out.println(temp1);
                        //System.out.println(temp1.length());
                        //m=temp1.length();
                        //System.out.println(m);
                        for(j=0;j<temp1.length();j++){
                                //System.out.println(j);
                                temp2=temp1.charAt(j);
                                //System.out.println(i);
                                //System.out.println(j);
                                //System.out.println(temp2);
                                item1_canditate.add(String.valueOf(temp2));
                        }
                }
        return item1_canditate.size();
    }
    
    //计算项目集支持度
    double count_sup(String x){
        int temp=0;
        for(int i=0;i<trans_set.length;i++){
            for(int j=0;j<x.length();j++){
                if(trans_set[i].indexOf(x.charAt(j))==-1)
                    break;
                else 
                    if(j==(x.length()-1))
                        temp++;
            }
        }
        return temp;
    }
    
    //构造1候选集合＆频繁集
    public void item1_gen(){
        String temp1="";
        double m=0;
        Iterator temp=canditate_set[0].iterator();
        while(temp.hasNext()){
            temp1=(String)temp.next();
            m=count_sup(temp1);
            if(m>=minsup*trans_set.length){
                frequent_set[0].add(temp1);
            }    
        }
    }
    
    //由k频繁集和1频繁集生成k+1候选集
    public void canditate_gen(int k){
        String y="",z="",m="";
        char c1='M',c2='M';
        Iterator temp1=frequent_set[k-2].iterator();
        Iterator temp2=frequent_set[0].iterator();
        TreeSet h=new TreeSet();
        while(temp1.hasNext()){
            y=(String)temp1.next();
            c1=y.charAt(y.length()-1);
            //System.out.println("y="+y);
            while(temp2.hasNext()){
                z=(String)temp2.next();    
                //System.out.println("z="+z);
                c2=z.charAt(0);
                
                if(c1>=c2) 
                    continue;
                else{
                    m=y+z;
                    h.add(m);
                    }
            }
            temp2=frequent_set[0].iterator();
        }
        canditate_set[k-1]=h;
    }
    
    //k候选集=>k频繁集
    public void frequent_gen(int k){
        String s1="";
        Iterator ix=canditate_set[k-1].iterator();
        while(ix.hasNext()){
            s1=(String)ix.next();
            if(count_sup(s1)>=(minsup*trans_set.length)){
                frequent_set[k-1].add(s1);
            }
        }
    }
    
    public boolean is_frequent_empty(int k){
        if(frequent_set[k-1].isEmpty())
            return true;
        else
            return false;
    }

    public boolean included(String s1,String s2){
        for(int i=0;i<s1.length();i++){
            if(s2.indexOf(s1.charAt(i))==-1)
                return false;
            else
                if(i==s1.length()-1)
                    return true;
        }
        return true;
    }
    //该类函数复杂度过高，有待改进算法！！
    public void maxfrequent_gen(){
        int i,j;
        Iterator iterator,iterator1,iterator2;
        String temp="",temp1="",temp2="";
        for(i=0;i<frequent_top;i++){
            max_frequent.addAll(frequent_set[i]);
        }
        for(i=0;i<frequent_top;i++){
            iterator1=frequent_set[i].iterator();
            while(iterator1.hasNext()){
                temp1=(String)iterator1.next();
                for(j=i+1;j<frequent_top;j++){
                    //System.out.println("i="+i+"\tj="+j);
                    //System.out.println(s[j+1]);
                    iterator2=frequent_set[j].iterator();
                    while(iterator2.hasNext()){
                        temp2=(String)iterator2.next();
                        if(included(temp1,temp2))
                            max_frequent.remove(temp1);
                    }
                }    
            }    
        }
    }

    public void print_maxfrequent(){
        Iterator iterator=max_frequent.iterator();
        System.out.print("最大频繁项集：");
        while(iterator.hasNext()){
            System.out.print((String)iterator.next()+"\t");
        }
        System.out.println();
    }
    
    public void subGen(String s){
        String x="",y="";
        for(int i=1;i< (1<<s.length())-1;i++){
            for(int j=0;j<s.length();j++){
                if(((1<<j)&i)!=0){
                    //System.out.print(s.charAt(j));
                    x+=s.charAt(j);
                }
            }
            //System.out.print("\t");
            for(int j=0;j<s.length();j++){
                if(((1<<j)&(~i))!=0){
                    //System.out.print(s.charAt(j));
                    y+=s.charAt(j);
                //System.out.println(x.trim()+"\t"+y.trim());
                }
            }    
            //System.out.println(x+"\t"+y);
            if(count_sup(x+y)/count_sup(x)>=minconf){
                rule.put(x,y);
            }
            x="";y="";
            
        }
    }
    
    public void ruleGen(){
        String s;
        Iterator iterator=max_frequent.iterator();
        while(iterator.hasNext()){
            s=(String)iterator.next();
            subGen(s);
        }
    }
    
    public void rulePrint(){
        String x,y;
        double temp=0;
        Set hs=rule.keySet();
        Iterator iterator=hs.iterator();
        System.out.println("关联规则：");
        while(iterator.hasNext()){
            x=(String)iterator.next();
            y=(String)rule.get(x);
            temp=(count_sup(x+y)/count_sup(x));
            System.out.println(x+"==>"+y+"\t"+temp);
        }
    }
    
    public void run(){
                int k=1;
                //myapriori run=new myapriori();
                item1_gen();
                do{
                        k++;
                        canditate_gen(k);
                        frequent_gen(k);
                }while(!is_frequent_empty(k));
                frequent_top=k-1;
        print_canditate();
        maxfrequent_gen();
        print_maxfrequent();
        ruleGen();
        rulePrint();
    
    }
    
    public static void main(String [] args){
        myapriori x=new myapriori();
        x.run();
    }

    //for test
    void print1(){
        Iterator temp=canditate_set[0].iterator();
        while(temp.hasNext())
            System.out.println(temp.next());    
    } 
    //for test
    void print2(){
        Iterator temp=frequent_set[0].iterator();
        while(temp.hasNext())
            System.out.println((String)temp.next());
    }
    //for test
    void print3(){
        canditate_gen(1);
        frequent_gen(2);
        Iterator temp=canditate_set[1].iterator();
        Iterator temp1=frequent_set[1].iterator();
        while(temp.hasNext())
            System.out.println("候选"+(String)temp.next());
        while(temp1.hasNext())
            System.out.println("频繁"+(String)temp1.next());
    }
    
    void print_canditate(){
        
        for(int i=0;i<frequent_set[0].size();i++){
            Iterator ix=canditate_set[i].iterator();
            Iterator iy=frequent_set[i].iterator();
            System.out.print("候选集"+(i+1)+":");
            while(ix.hasNext()){
                System.out.print((String)ix.next()+"\t");
            }
            System.out.print("\n"+"频繁集"+(i+1)+":");
            while(iy.hasNext()){
                System.out.print((String)iy.next()+"\t");
            }
            System.out.println();
        }
    }    

/*    //main function for test
    public static void main(String [] args){
    myapriori run=new myapriori();
    run.item1_gen();
    run.print2();
    run.print3();
    }
*/

}