//DataModel 可以有很多種,實現abstractDataMode的子類,原則上都可以作爲數據源,個人覺得,不管是那種DataMode各自有優缺點
//應該視情況而定,
package com.test.mahout;
import java.util.List;
import org.apache.mahout.cf.taste.impl.common.FastByIDMap;
import org.apache.mahout.cf.taste.impl.model.GenericDataModel;
import org.apache.mahout.cf.taste.impl.model.GenericUserPreferenceArray;
import org.apache.mahout.cf.taste.impl.neighborhood.NearestNUserNeighborhood;
import org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender;
import org.apache.mahout.cf.taste.impl.similarity.PearsonCorrelationSimilarity;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.model.PreferenceArray;
import org.apache.mahout.cf.taste.neighborhood.UserNeighborhood;
import org.apache.mahout.cf.taste.recommender.RecommendedItem;
import org.apache.mahout.cf.taste.recommender.Recommender;
import org.apache.mahout.cf.taste.similarity.UserSimilarity;
class RecommenderIntro {
public static void main(String[] args) throws Exception {
/* FastByIDMap<PreferenceArray> preferences =new FastByIDMap<PreferenceArray>();
*
PreferenceArray prefsForUser1 = new GenericUserPreferenceArray(10); A
prefsForUser1.setUserID(0, 1L);
prefsForUser1.setItemID(0, 101L); B
prefsForUser1.setValue(0, 3.0f); B
prefsForUser1.setItemID(1, 102L);
prefsForUser1.setValue(1, 4.5f);
… (8 more)
preferences.put(1L, prefsForUser1); C
DataModel model = new GenericDataModel(preferences); D
//A Set up PreferenceArray for user 1
//B Add the first of 10 preferences
//C Attach user 1’s preference*/
// laod Data File
// DataModel model = new FileDataModel(new File("C:\\mahout_data.txt"));
FastByIDMap<PreferenceArray> preferences =new FastByIDMap<PreferenceArray>();
/*FastByIDMap是經過優化了的key-value數據結夠,在這裏用來存儲基本的元數據,《mahout in action》書中對這個數據結構做了詳細的解釋*/
PreferenceArray prefsForUser1=new GenericUserPreferenceArray(3);//注意這裏的數字
// 這裏是用來存儲一個用戶的元數據,這些元數據通常來自日誌文件,比如瀏覽歷史,等等,不同的業務場合,它的業務語義應該是不一樣
prefsForUser1.setUserID(0, 1);/*個人對這裏也感覺到非常模糊,其實這裏保存用戶ID完全用不着key-value結構,也用不着用一個long型的ID,這裏個人覺得是爲了以後擴展或者,保持統一的格式,注意用就是了*/
prefsForUser1.setItemID(0, 101);
prefsForUser1.setValue(0, 5.0f);
prefsForUser1.setItemID(1, 102);
prefsForUser1.setValue(1, 3.0f);
prefsForUser1.setItemID(2, 103);
prefsForUser1.setValue(2, 2.5f);
preferences.put(1l, prefsForUser1);//在這裏添加數據
PreferenceArray prefsForUser2=new GenericUserPreferenceArray(4);
prefsForUser2.setUserID(0, 2);
prefsForUser2.setItemID(0, 101);
prefsForUser2.setValue(0, 2.0f);
prefsForUser2.setItemID(1, 102);
prefsForUser2.setValue(1,2.5f);
prefsForUser2.setItemID(2, 103);
prefsForUser2.setValue(2,5.0f);
prefsForUser2.setItemID(3,104);
prefsForUser2.setValue(3,2.0f);
preferences.put(2l, prefsForUser2);
PreferenceArray prefsForUser3=new GenericUserPreferenceArray(4);
prefsForUser3.setUserID(0, 3);
prefsForUser3.setItemID(0, 101);
prefsForUser3.setValue(0, 2.5f);
prefsForUser3.setItemID(1, 104);
prefsForUser3.setValue(1, 4.0f);
prefsForUser3.setItemID(2, 105);
prefsForUser3.setValue(2, 4.5f);
prefsForUser3.setItemID(3, 107);
prefsForUser3.setValue(3, 5.0f);
preferences.put(3l, prefsForUser3);
PreferenceArray prefsForUser4=new GenericUserPreferenceArray(4);
prefsForUser4.setUserID(0, 4);
prefsForUser4.setItemID(0,101);
prefsForUser4.setValue(0, 5.0f);
prefsForUser4.setItemID(1,103);
prefsForUser4.setValue(1, 3.0f);
prefsForUser4.setItemID(2,104);
prefsForUser4.setValue(2,4.5f);
prefsForUser4.setItemID(3, 106);
prefsForUser4.setValue(3, 4.0f);
preferences.put(4l, prefsForUser4);
PreferenceArray prefsForUser5=new GenericUserPreferenceArray(6);
prefsForUser5.setUserID(0, 5);
prefsForUser5.setItemID(0, 101);
prefsForUser5.setValue(0, 4.0f);
prefsForUser5.setItemID(1, 102);
prefsForUser5.setValue(1, 3.0f);
prefsForUser5.setItemID(2, 103);
prefsForUser5.setValue(2, 2.0f);
prefsForUser5.setItemID(3, 104);
prefsForUser5.setValue(3, 4.0f);
prefsForUser5.setItemID(4, 105);
prefsForUser5.setValue(4, 3.5f);
prefsForUser5.setItemID(5, 106);
prefsForUser5.setValue(5, 4.0f);
preferences.put(5l, prefsForUser5);
DataModel model=new GenericDataModel(preferences) ;//DataModel的建立
UserSimilarity similarity = new PearsonCorrelationSimilarity(model);
UserNeighborhood neighborhood = new NearestNUserNeighborhood(2,similarity, model);
// Create the recommender engine
Recommender recommender = new GenericUserBasedRecommender(model,neighborhood, similarity);
// C For user 1, recommend 1 item
List<RecommendedItem> recommendations = recommender.recommend(1, 1);
for (RecommendedItem recommendation : recommendations) {
System.out.println(recommendation);
}
}
}