数据挖掘之关联规则Apriori算法

/*
关联规则Apriori算法思想: 假如有一个大小为20的样本，每个样本包含I1,I2,I3,I4,I5其中的某些属性，假如A样本为{I1,I2,I3},B样本为{I1,I2,I4}之类的，设置最小支持度为2，即选择出来的频繁项集的所有属性至少有2个样本全部包含，比如频繁项集{I1,I2},此时A和B都包含，当然其他的样本也可能包含。那么这个频繁项集是符合的，那么我们可以认为I1和I2的关联性是
比较强的。直到找到大小最大的频繁项集。
*/
#include<cstdio>
#include<iostream>
#include<string>
#include<vector>
#include<cstring>
#include<map>
#include<algorithm>
using namespace std;
#define UINT_MAX 100
class Apriori{
public:
    Apriori(size_t is=0,unsigned int mv=0){
        item_size=is;
        min_value=mv;
    }
    ~Apriori(){}
    void getItem();
    /**求事务的频繁项**/
    map<vector<string>,unsigned int> find_freitem();
    /**连接两个k-1级频繁项，得到第k级频繁项**/
    map<vector<string>,unsigned int> apri_gen(unsigned int K,map<vector<string>,unsigned int> K_item);
    /**展示频繁项集**/
    void showAprioriItem(unsigned int K,map<vector<string>,unsigned int> showmap);
private:
    map<int,vector<string> > item; /**存储所有最开始的事务及其项**/
    map<vector<string>,unsigned int> K_item; /**存储频繁项集**/
    size_t item_size;      /**事务数**/
    unsigned int min_value;  /**最小支持度**/
};
void Apriori::getItem(){
    int ci=item_size;
    for(int i=0;i<ci;i++){
        string str;
        vector<string> temp;
        cout<<"请输入第"<<i+1<<"个事务的项集(123 end):";
        while(cin>>str&&str!="123"){
            temp.push_back(str);
        }
        sort(temp.begin(),temp.end());
        pair< map<int,vector<string> >::iterator,bool> ret=item.insert(make_pair(i+1,temp));
        if(!ret.second){ /**插入失败**/
            --i;
            cout<<"你输入的元素已存在!请重新输入!"<<endl;
        }
    }
    cout<<"--------------运行结果如下:--------------"<<endl;
}
map<vector<string>,unsigned int> Apriori::find_freitem(){
    unsigned int i=1;
    bool isEmpty=false;

    map<int,vector<string> >::iterator mit;
    for(mit=item.begin();mit!=item.end();mit++){
        vector<string> vec=mit->second;
        if(vec.size()!=0) break; /**找到第一个非空的事务**/
    }
    if(mit==item.end()){
        isEmpty=true;
        cout<<"事务集为空!程序无法进行..."<<endl;
        map<vector<string>,unsigned int> empty;
        return empty;
    }
    while(1){
        map<vector<string>,unsigned int> K_itemTemp=K_item;
        K_item=apri_gen(i++,K_item);
        if(K_itemTemp==K_item){ /****/
            i=UINT_MAX;
            break;
        }
        map<vector<string>,unsigned int> pre_K_item=K_item;
        size_t Kitemsize=K_item.size();
        if(Kitemsize!=1&&i!=1){
            vector<map<vector<string>,unsigned int>::iterator> eraseVecMit;
            map<vector<string>,unsigned int>::iterator pre_K_item_it1=pre_K_item.begin(),pre_K_item_it2;
            while(pre_K_item_it1!=pre_K_item.end()){
                map<vector<string>,unsigned int>::iterator mit=pre_K_item_it1;
                bool isExist=true;
                vector<string> vec1;
                vec1=pre_K_item_it1->first;
                vector<string> vec11(vec1.begin(),vec1.end()-1);/**除了最后一项**/
                while(mit!=pre_K_item.end()){
                    vector<string> vec2;
                    vec2=mit->first;
                    vector<string> vec22(vec2.begin(),vec2.end()-1);
                    if(vec11==vec22) break; /**找到第一个相等的**/
                    ++mit;
                }
                if(mit==pre_K_item.end()) isExist=false;  /**不存在**/
                if(!isExist&&pre_K_item_it1!=pre_K_item.end()) /**该项可以删除**/
                    eraseVecMit.push_back(pre_K_item_it1);
                ++pre_K_item_it1; /**继续下一个**/
            }
            size_t eraseSetSize=eraseVecMit.size();
            if(eraseSetSize==Kitemsize) break; /**频繁项集全部应该被删除，则退出**/
            else{
                vector<map<vector<string>,unsigned int>::iterator >::iterator currentErs=eraseVecMit.begin();
                while(currentErs!=eraseVecMit.end()){ /**删除应该删除的项集**/
                    map<vector<string>,unsigned int>::iterator eraseMit=*currentErs;
                    K_item.erase(eraseMit);
                    ++currentErs;
                }
            }
        }
        else if(Kitemsize==1) break;/**只剩下一个频繁项集也退出**/

    }
    cout<<endl;
    showAprioriItem(i,K_item);
    return K_item;
}
map<vector<string>,unsigned int> Apriori::apri_gen(unsigned int K,map<vector<string>,unsigned int> K_item){
    if(1==K){ /**候选集C1**/
        size_t c1=item_size;
        map<int,vector<string> >::iterator mapit=item.begin();
        vector<string> vec;
        map<string,unsigned int> c1_itemtemp;
        while(mapit!=item.end()){
            vector<string> temp=mapit->second; /**事务中的项目**/
            vector<string>::iterator vecit=temp.begin();
            while(vecit!=temp.end()){
                pair<map<string,unsigned int>::iterator,bool> ret=c1_itemtemp.insert(make_pair(*vecit++,1));
                if(!ret.second){
                    ++ret.first->second; /**该项目出现的个数加1**/
                }
            }
            ++mapit;
        }
        map<string,unsigned int>::iterator item_it=c1_itemtemp.begin();
        map<vector<string>,unsigned int> c1_item;
        while(item_it!=c1_itemtemp.end()){
            vector<string> temp;
            if(item_it->second>=min_value){ /**大于最小支持度的才加入到1-频繁项目集**/
                temp.push_back(item_it->first);
                c1_item.insert(make_pair(temp,item_it->second));
            }
            ++item_it;
        }
        return c1_item;
    }
    else{
        cout<<endl;
        showAprioriItem(K-1,K_item); /**显示(k-1)-频繁项目集**/
        map<vector<string>,unsigned int>::iterator ck_item_it1=K_item.begin(),ck_item_it2;
        map<vector<string>,unsigned int> ck_item;
        while(ck_item_it1!=K_item.end()){
            ck_item_it2=ck_item_it1;
            ++ck_item_it2;
            map<vector<string>,unsigned int>::iterator mit=ck_item_it2;

            while(mit!=K_item.end()){
                vector<string> vec,vec1,vec2;
                vec1=ck_item_it1->first;
                vec2=mit->first;
                vector<string>::iterator vit1,vit2;
                vit1=vec1.begin();
                vit2=vec2.begin();
                while(vit1<vec1.end()&&vit2<vec2.end()){
                    string str1=*vit1;
                    string str2=*vit2;
                    ++vit1;
                    ++vit2;
                    if(K==2||str1==str2){
                        if(vit1!=vec1.end()&&vit2!=vec2.end()){
                            vec.push_back(str1);
                        }
                    }
                    else break;
                }
                if(vit1==vec1.end()&&vit2==vec2.end()){ /**前K-1项相同**/
                    --vit1;
                    --vit2;
                    string str1=*vit1;
                    string str2=*vit2;
                    if(str1>str2){ /**再插入**/
                        vec.push_back(str2);
                        vec.push_back(str1);
                    }
                    else{
                        vec.push_back(str1);
                        vec.push_back(str2);
                    }
                    map<int,vector<string> >::iterator base_item=item.begin();
                    unsigned int Acount=0;
                    while(base_item!=item.end()){
                        unsigned int count=0,mincount=UINT_MAX;
                        vector<string> vv=base_item->second;
                        vector<string>::iterator vecit,bvit;
                        for(vecit=vec.begin();vecit<vec.end();vecit++){
                            string t=*vecit;
                            count=0;
                            for(bvit=vv.begin();bvit<vv.end();bvit++){
                                if(t==*bvit) count++;
                            }
                            mincount=(count<mincount?count:mincount);
                        }
                        if(mincount>=1&&mincount!=UINT_MAX) /**该项集是该事务的子集**/
                            Acount+=mincount;
                        ++base_item;
                    }
                    if(Acount>=min_value&&Acount!=0){ /**大于等于最小支持度**/
                        sort(vec.begin(),vec.end());
                        pair<map<vector<string>,unsigned int>::iterator,bool> ret=ck_item.insert(make_pair(vec,Acount));
                        if(!ret.second){
                            ret.first->second+=Acount;
                        }
                    }
                }
                ++mit;
            }
            ++ck_item_it1;
        }
        if(ck_item.empty()) return K_item;
        else return ck_item;
    }
}
void Apriori::showAprioriItem(unsigned int K,map<vector<string>,unsigned int> showmap){
    map<vector<string>,unsigned int>::iterator showit=showmap.begin();
    if(K!=UINT_MAX) cout<<endl<<"第 "<<K<<" 级频繁项集为:"<<endl;
    else cout<<"最终的频繁项集为:"<<endl;
    cout<<"项 集"<<"  	  "<<"频率"<<endl;
    while(showit!=showmap.end()){
        vector<string> vec=showit->first;
        vector<string>::iterator vecit=vec.begin();
        cout<<"{";
        while(vecit!=vec.end()){
            cout<<*vecit<<" ";
            ++vecit;
        }
        cout<<"}"<<" 	 ";
        cout<<showit->second<<endl;
        ++showit;
    }
}
unsigned int parseNumber(const char *str){
    if(str==NULL) return 0;
    else{
        unsigned int num=0;
        size_t len=strlen(str);
        for(size_t i=0;i<len;i++){
            num*=10;
            if(str[i]>='0'&&str[i]<='9') num+=str[i]-'0';
            else return 0;
        }
        return num;
    }
}

int main(){
    /*
    unsigned int itemsize=0;
    unsigned int min;
    do{
        cout<<"请输入事务数:";
        char *str=new char;
        cin>>str;
        itemsize=parseNumber(str); //事务数
        if(itemsize==0){
            cout<<"请输入大于0正整数!"<<endl;
        }
    }while(itemsize==0);

    do{
        cout<<"请输入最小阈值:";
        char *str=new char;
        cin>>str;
        min=parseNumber(str);    //最小支持度
        if(min==0){
            cout<<"请输入大于0正整数!"<<endl;
        }
    }while(min==0);

    Apriori a(itemsize,min);
    a.getItem();
    map<vector<string>,unsigned int> AprioriMap=a.find_freitem(); //找到频繁项目集
    a.showAprioriItem(UINT_MAX,AprioriMap);
    */
    return 0;
}