package?org.apache.mahout.cf.taste.hadoop.svd;
/*
?*?Licensed?to?the?Apache?Software?Foundation?（ASF）?under?one?or?more
?*?contributor?license?agreements.??See?the?NOTICE?file?distributed?with
?*?this?work?for?additional?information?regarding?copyright?ownership.
?*?The?ASF?licenses?this?file?to?You?under?the?Apache?License?Version?2.0
?*?（the?“License“）;?you?may?not?use?this?file?except?in?compliance?with
?*?the?License.??You?may?obtain?a?copy?of?the?License?at
?*
?*?????http://www.apache.org/licenses/LICENSE-2.0
?*
?*?Unless?required?by?applicable?law?or?agreed?to?in?writing?software
?*?distributed?under?the?License?is?distributed?on?an?“AS?IS“?BASIS
?*?WITHOUT?WARRANTIES?OR?CONDITIONS?OF?ANY?KIND?either?express?or?implied.
?*?See?the?License?for?the?specific?language?governing?permissions?and
?*?limitations?under?the?License.
?*/

import?java.io.IOException;
import?java.util.Iterator;

import?org.apache.hadoop.io.FloatWritable;
import?org.apache.hadoop.io.LongWritable;
import?org.apache.hadoop.mapreduce.Mapper;
import?org.apache.hadoop.mapred.OutputCollector;
import?org.apache.hadoop.mapred.Reporter;
import?org.apache.mahout.math.Vector;
import?org.apache.mahout.math.VectorWritable;

public?class?AverageUserRatingMapper?extends?
??Mapper?{

??public?void?map（LongWritable?userID?VectorWritable?userVector
??????OutputCollector?output?Reporter?reporter）
????throws?IOException?{
????
????//initialise?variables
????float?sum?=?0;?
????int?count?=?0;
??????
????//iterate?through?user?vector?
????Iterator?userVectorIterator?=?userVector.get（）.iterateNonZero（）;
????while?（userVectorIterator.hasNext（））?{
??????//add?up?all?non-zero?user?prefs
??????sum?+=?userVectorIterator.next（）.index（）;
??????//count?how?many?prefs?there?are
??????count++;
????}
??????
????//calculate?average?user?pref
????float?avgUserPref?=?sum?/?count;
????//output?key?=?userID?value?=?average?user?pref
????output.collect（userID?new?FloatWritable（avgUserPref））;
??
??}??
??
}

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????2417??2010-09-25?02:20??svd?java\svd\pom.xml

?????文件???????2086??2010-08-09?09:38??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\AverageUserRatingMapper.java

?????文件???????1941??2010-08-09?09:38??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\AvgItemPrefMapper.java

?????文件???????1914??2010-08-09?09:38??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\AvgItemPrefReducer.java

?????文件???????2380??2010-08-25?21:43??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\CardinalityCorrectionMapper.java

?????文件???????5747??2010-09-29?18:54??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\DistributedSVDItemRecommenderJob.java

?????文件???????8731??2010-09-29?18:26??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\DistributedSVDRecommenderJob.java

?????文件???????1541??2010-09-29?18:54??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\SVDItemItemSimilarityJob.java

?????文件???????2644??2010-09-29?18:27??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\SVDItemItemSimilarityJobMapper.java

?????文件???????1683??2010-09-29?18:27??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\SVDItemItemSimilarityJobReducer.java

?????文件???????1736??2010-09-29?18:54??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\SVDItemRecommenderReducer.java

?????文件???????3547??2010-09-29?18:24??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\SVDPredictionJob.java

?????文件???????2995??2010-09-29?18:26??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd\SVDRecommenderMapper.java

?????文件???????8172??2010-09-29?18:54??svd?java\svd\src\test\java\org\apache\mahout\cf\taste\hadoop\svd\SVDItemItemSimilarityJobMapperTest.java

?????文件???????3266??2010-09-29?18:54??svd?java\svd\src\test\java\org\apache\mahout\cf\taste\hadoop\svd\SVDItemItemSimilarityJobReducerTest.java

?????目錄??????????0??2010-09-29?18:54??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop\svd

?????目錄??????????0??2010-09-29?18:56??svd?java\svd\src\test\java\org\apache\mahout\cf\taste\hadoop\svd

?????目錄??????????0??2010-08-11?05:35??svd?java\svd\src\main\java\org\apache\mahout\cf\taste\hadoop

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\test\java\org\apache\mahout\cf\taste\hadoop

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\main\java\org\apache\mahout\cf\taste

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\test\java\org\apache\mahout\cf\taste

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\main\java\org\apache\mahout\cf

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\test\java\org\apache\mahout\cf

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\main\java\org\apache\mahout

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\test\java\org\apache\mahout

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\main\java\org\apache

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\test\java\org\apache

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\main\java\org

?????目錄??????????0??2010-08-09?09:36??svd?java\svd\src\test\java\org

?????目錄??????????0??2010-09-29?18:55??svd?java\svd\src\main\java

............此處省略9個文件信息