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From 冯伟 <whitepapers...@gmail.com>
Subject How to index by long ID in RandomAccessSparseVector
Date Tue, 08 May 2012 08:13:38 GMT
I have read some code about item-based recommendation in version-0.6,
starting from "org.apache.mahout.cf.taste.
hadoop.item.RecommenderJob". I found that there is a Long-to-Int mapping
provided by the function "int TasteHadoopUtils.idToIndex(long)".
Long-to-Int is performed both on userId and itemId. I wonder if it possible
to have two long mapped into one int? If it is the case, then we would
likely to merge vectors from different itemids/uids, right? This is quite
confusing.

Is it better to provide a RandomAccessSparseVector implemented by
OpenLongDoubleHashMap instead of OpenIntDoubleHashMap? Thanks in advance.

----------------------
Wei Feng

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