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https://issues.apache.org/jira/browse/MAHOUT-432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12884318#action_12884318
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Hui Wen Han commented on MAHOUT-432:
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The input is not cleared,because it can more accurately calculate user's
similarity using all or most items in preferences than only using valid or new
items in preferences.
the change seems that it not much large,
we can just skip those items that are not in itemsFile when we add item to
topItems.
Queue<RecommendedItem> topItems = new
PriorityQueue<RecommendedItem>(recommendationsPerUser + 1,
102
Collections.reverseOrder(ByValueRecommendedItemComparator.getInstance()));
103
104 Iterator<Vector.Element> recommendationVectorIterator =
105 recommendationVector.iterateNonZero();
106 while (recommendationVectorIterator.hasNext()) {
107 Vector.Element element = recommendationVectorIterator.next();
108 int index = element.index();
109 float value = (float) element.get();
110 if (!Float.isNaN(value)) {
111 if (topItems.size() < recommendationsPerUser) {
112 topItems.add(new GenericRecommendedItem(indexItemIDMap.get(index),
value));
113 } else if (value > topItems.peek().getValue()) {
114 topItems.add(new GenericRecommendedItem(indexItemIDMap.get(index),
value));
115 topItems.poll();
116 }
117 }
118 }
> Can add one parameter --itemsFile for
> org.apache.mahout.cf.taste.hadoop.item.RecommenderJob
> --------------------------------------------------------------------------------------------
>
> Key: MAHOUT-432
> URL: https://issues.apache.org/jira/browse/MAHOUT-432
> Project: Mahout
> Issue Type: New Feature
> Components: Collaborative Filtering
> Affects Versions: 0.4
> Reporter: Hui Wen Han
> Assignee: Sean Owen
> Priority: Minor
> Fix For: 0.4
>
>
> Can add one parameter --itemsFile for
> org.apache.mahout.cf.taste.hadoop.item.RecommenderJob ?
> --itemsFile some likes the the --usersFile.
> in some case, we want to calculate similarity using all preferences data ,
> but some item in preferences are old ,not available,behind the times or
> retired ,
> we want that those data can not recommend to users, can only recommend user
> with new or valid items.
> so we can add on paramete --itemsFile for RecommenderJob, itemsFile includes
> all the new valid items.
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