FindZero.cpp

class FindZero {
private:
    ifstream fin;
    ofstream fout;
    clock_t start;
    const string userFactorsFile = "user_factors";
    const string itemFactorsFile = "item_factors";
    const string zeroFile = "zero_list.txt";
    map<ll, int> userMap, itemMap;
    vector<vector<double> > users, items;
    const int factors = 30;
    
    const double threshold = 0.05;
    
public:
    void run() {
        clockInit("readFactor");
        read(userFactorsFile, users, userMap);
        read(itemFactorsFile, items, itemMap);
        printDurating("readFactor");
        
        clockInit("makeZeroFile");
        makeZeroFile();
        printDurating("makeZeroFile");
    }
    
    void makeZeroFile() {
        fout.open(zeroFile);
        for(auto &i: userMap) {
            if(i.first % 5000 == 0) {
                cout << "now : " << i.first << endl;
            }
            for(auto&j: itemMap) {
                double ret = multifly(i.second, j.second);
                if(ret < threshold) {
                    fout << i.first << " " << j.first << endl;
                }
            }
        }
        fout.close();
    }
    
    double multifly(ll userI, ll userJ) {
        int userIdx = userMap[userI];
        int itemIdx = itemMap[userJ];
        
        double ret = 0.0;
        for(int i=0;i<factors;i++) {
            ret += users[userIdx][i]*items[itemIdx][i];
        }
        return ret;
    }
    
    double multifly(int userIdx, int itemIdx) {
        double ret = 0.0;
        for(int i=0;i<factors;i++) {
            ret += users[userIdx][i]*items[itemIdx][i];
        }
        return ret;
    }
    
    void read(string filename, vector<vector<double> >& mat, map<ll, int>& mp) {
        fin.open(filename);
        while(!fin.eof()) {
            ll userId;
            fin >> userId;
            vector<double> row;
            for(int i=0;i<factors; i++) {
                double tmp;
                fin >> tmp;
                row.push_back(tmp);
            }
            mat.push_back(row);
            mp[userId] = (int)mat.size()-1;
        }
        fin.close();
    }
    
    void clockInit(string name) {
        cout << "[" << name << "] :: Start" <<  endl;
        start = clock();
    }
    void printDurating(string name) {
        cout << "["<<name << "] :: End / duration : " << (clock() - start ) / (double) CLOCKS_PER_SEC << endl;
    }
};