Difference between User-Based and Item-Basedhttp : //www.gooseeker.com/en/node/knowledgebase/colfiltering https://en.wikipedia.org/wiki/Collaborative_filtering
http://www.gooseeker.com/en/ node/knowledgebase/colfiltering http://my.oschina.net/BreathL/blog/62519?p=2#comments http://download.csdn.net/download/icgreen/7484081 User-recommended collaborative filtering recommendations for European algorithms java version http://www.cnblogs.com/kunpengit/archive/2013/03/04/2942684.html ------------------------- ---------------------------------- package com.wk.xietongguolue; import java.util.HashMap; import java .util.HashSet; import java.util.Iterator; import java.util.Map; import java.util.Set; public class Data {
static String[] films = { "House of Flying Daggers", "All the way to the north", "The girl we chased together in those years", "CCAV", "If You Are the One" };
static String[] users = { "aaa", "bbb", "ccc", "ddd", "Ge Erdan" };
static Map score = new HashMap();
static Set userSet = new HashSet();
static Set filmSet = new HashSet();
static {
for ( String str : Data.users) {
userSet.add(str);
}
for (String str : Data.films) {
filmSet.add(str);
}
score = getScore();
}
public static void outNearbyUserList(String user) {
Map scores = new HashMap();
for (String tempUser : users) {
if (tempUser.equalsIgnoreCase(user)) {
continue;
}
double score = getOSScore(user, tempUser);
scores.put(tempUser, score);
}
System.out.println(scores.toString());
}
private static Double getOSScore(String user1, String user2) {
HashMap user1Score = (HashMap) score.get(user1);
HashMap user2Score = (HashMap) score.get(user2);
double totalscore = 0.0;
Iterator it = user1Score.keySet().iterator();
while (it.hasNext()) {
String film = (String) it.next();
int a1 = (Integer) user1Score.get(film);
int a2 = (Integer) user1Score.get(film);
int b1 = (Integer) user2Score.get(film);
int b2 = (Integer) user2Score.get(film);
int a = a1 * a2 - b1 * b2;
//System.out.println(Math.abs(a));
totalscore += Math.sqrt(Math.abs(a));
}
return totalscore;
}
private static Map getScore() {
Map score = new HashMap();
// aaa
HashMap tempScore = new HashMap();
tempScore.put(films[0], 9);
tempScore.put(films[1], 1);
tempScore.put(films[2], 9);
tempScore.put(films[3], 7);
tempScore.put(films[4], 1);
score.put(Data.users[0], tempScore);
// bbb
tempScore = new HashMap();
tempScore.put(films[0], 2);
tempScore.put(films[1], 9);
tempScore.put(films[2], 2);
tempScore.put(films[3], 2);
tempScore.put(films[4], 2);
score.put(Data.users[1], tempScore);
// ccc
tempScore = new HashMap();
tempScore.put(films[0], 9);
tempScore.put(films[1], 9);
tempScore.put(films[2], 9);
tempScore.put(films[3], 3);
tempScore.put(films[4], 3);
score.put(Data.users[2], tempScore);
// ddd
tempScore = new HashMap();
tempScore.put(films[0], 4);
tempScore.put(films[1], 9);
tempScore.put(films[2], 9);
tempScore.put(films[3], 4);
tempScore.put(films[4], 4);
score.put(Data.users[3], tempScore);
// 葛二蛋
tempScore = new HashMap();
tempScore.put(films[0], 5);
tempScore.put(films[1], 5);
tempScore.put(films[2], 5);
tempScore.put(films[3], 5);
tempScore.put(films[4], 5);
score.put(Data.users[4], tempScore);
return score;
}
public static void main(String[] args) {
//
System.out.println(Data .users[0] + " Similarity with other people (the lower the score, the more similar): ");
Data.outNearbyUserList(Data.users[0]);
}
}
User-Based Collaborative Filtering Recommendations Based on European Algorithms
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