技術標籤：java演算法資料探勘Apriori關聯規則

實驗結果

最小支援度為0.005時只需10s即可得到結果並且輸出所有頻繁項集

程式碼

package com.company;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.*;

public class Main {
 

    private static final ArrayList<int[]> data = new ArrayList();
    private static final HashMap<String, Integer> fir = new HashMap<>();
    private static double SUPPORT_PERCENT;
    private static int[] a;
    private static int[] b;
    private static int Firlen;
    private static
 
 int Datalen;
    private static int sum = 0;
    private static List<List<Integer>> ck = new ArrayList<>();

    public static void main(String[] args) throws IOException {
        // write your code here
        Scanner s = new Scanner(System.in);
        SUPPORT_PERCENT = s.nextDouble
 
();
        long startTime = System.currentTimeMillis();
        loadData();
        SUPPORT_PERCENT = SUPPORT_PERCENT * data.size();
        a = new int[Firlen];
        b = new int[Firlen * (Firlen - 1) / 2];
        Countandhash();
        com();
        showfir();
        while (ck.size() > 1) {
            link();
            if (ck.size() == 0)
                break;
            tradata();
            showitem();
            delete();

            System.out.println("總數：" + sum);
        }
        long endTime = System.currentTimeMillis();
        System.out.println("程式執行時間：" + (endTime - startTime) + "ms");
    }

    private static void loadData() throws IOException {
        try (InputStreamReader reader = new InputStreamReader(new FileInputStream("retail.dat"),
                StandardCharsets.UTF_8)
        ) {

            BufferedReader bufferedReader = new BufferedReader(reader);
            String line;
            while ((line = bufferedReader.readLine()) != null) {

                String[] temp = line.split(" ");
                int[] arrayList = new int[temp.length];
                Datalen += temp.length;
                for (int i = 0; i < temp.length; i++) {
                    arrayList[i] = Integer.parseInt(temp[i]);
                    if (fir.get(temp[i]) == null)
                        fir.put(temp[i], 1);
                    else
                        fir.put(temp[i], fir.get(temp[i]) + 1);

                }
                data.add(arrayList);
            }
            Firlen = fir.size();
        }
    }

    public static void Countandhash() {

        for (int[] array :
                data) {
            if (array.length > 1) {
                for (int i = 0; i < array.length - 1; i++) {
                    for (int j = i + 1; j < array.length; j++) {
                        int temp = (array[i] * (Firlen - 1) + array[j]) %
                                (Datalen + 1);
                        b[temp]+=1;
                    }
                }
            }
            for (int j : array) {
                a[j] += 1;
            }
        }
    }

    public static void com() {
        for (int i = 0; i < a.length; i++) {
            List<Integer> list = new ArrayList<>();
            if (a[i] >= SUPPORT_PERCENT)
                list.add(i);
            else
                continue;
            ck.add(list);
        }
    }

    public static void showfir() {
        int count = 0;
        System.out.println("1項集如下：");
        for (int i = 0; i < a.length; i++) {
            if (a[i] >= SUPPORT_PERCENT) {
                count++;
                System.out.println("{" + i + "}:" + (double) a[i] / Datalen);
            }
        }
        System.out.println("1項集個數：" + count);
        sum += count;
    }

    public static void link() {
        List<Integer> t1 = new ArrayList<>();
        List<List<Integer>> t2 = new ArrayList<>();
        if (ck.get(0).size() == 1) {
            for (int i = 0; i < ck.size() - 1; i++) {
                for (int j = i + 1; j < ck.size(); j++) {
                    int temp = (ck.get(i).get(0) * (Firlen - 1) + ck.get(j).get(0)) %
                            (Datalen + 1);
                    if (b[temp] >= SUPPORT_PERCENT) {
                        t1.add(ck.get(i).get(0));
                        t1.add(ck.get(j).get(0));
                        t1.add(0);
                        t2.add(t1);
                        //t1.clear();
                        t1 = new ArrayList<>();
                    }
                }
            }
            ck = t2;
        } else {
            for (int i = 0; i < ck.size() - 1; i++) {
                for (int j = i + 1; j < ck.size(); j++) {
                    int t = 0;
                    while (t < ck.get(0).size() - 1) {
                        if (Objects.equals(ck.get(i).get(t), ck.get(j).get(t)))
                            t1.add(ck.get(i).get(t));
                        else
                            break;
                        t++;
                    }
                    if (t == ck.get(0).size() - 1) {
                        t1.add(ck.get(i).get(ck.get(0).size() - 1));
                        t1.add(ck.get(j).get(ck.get(0).size() - 1));
                        t1.add(0);
                        t2.add(t1);
                        t1 = new ArrayList<>();
                    } else
                        t1 = new ArrayList<>();
                }
            }
        }
        if (t2.size() != 0 && t2.get(0).size() >= 4) {
            List<List<Integer>> t3 = new ArrayList<List<Integer>>();
            for (List<Integer> integers : t2) {
                List<Integer> temp = new ArrayList<>();
                for (int j = 1; j < t2.get(0).size() - 1; j++) {
                    temp.add(t2.get(0).get(j));
                }
                for (List<Integer> integerList : ck) {
                    int n = 0;
                    while (Objects.equals(integerList.get(n), temp.get(n))) {
                        n++;
                        if (n == temp.size()) {
                            for (int k = 0; k < t2.get(0).size(); k++) {
                                t1.add(integers.get(k));
                            }
                            t3.add(t1);
                            t1 = new ArrayList<>();
                            break;
                        }
                    }
                    if (n == temp.size()) {
                        break;
                    }
                }
            }
            ck = t3;
        } else
            ck = t2;
    }

    public static void tradata() {
        for (int[] datum : data) {
            int m = 0;
            while (m < ck.size()) {
                if (ck.get(m).get(1) <= datum[datum.length - 1]) {
                    int n = 0;
                    for (int i : datum) {
                        if (ck.get(m).get(n) < i)
                            break;
                        else {
                            if (i == ck.get(m).get(n)) {
                                n++;
                                if (n == ck.get(m).size() - 1) {
                                    int temp = ck.get(m).get(n) + 1;
                                    ck.get(m).set(n, temp);
                                    break;
                                }
                            }
                        }
                    }
                }
                m++;
            }
        }
    }

    public static void showitem() {
        int co = 0;
        System.out.println(ck.get(0).size() - 1 + "項集如下：");
        for (List<Integer> integers : ck) {
            if (integers.get(integers.size() - 1) >= SUPPORT_PERCENT) {
                co++;
                System.out.print("{");
                for (int j = 0; j < integers.size() - 1; j++) {
                    System.out.print(integers.get(j) + " ");
                }
                System.out.println("}:" + (double) integers.get(integers.size() - 1) / Datalen);
            }
        }
        System.out.println(ck.get(0).size() - 1 + "項集個數:" + co);
        sum += co;
    }

    public static void delete() {
        List<List<Integer>> t2 = new ArrayList<>();
        for (List<Integer> integers : ck) {
            List<Integer> t1 = new ArrayList<>();
            if (integers.get(integers.size() - 1) >= SUPPORT_PERCENT) {
                for (int j = 0; j < integers.size() - 1; j++) {
                    t1.add(integers.get(j));
                }
            } else
                continue;
            t2.add(t1);
        }
        ck = t2;
    }
}