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Posted to dev@mahout.apache.org by "Sean Owen (JIRA)" <ji...@apache.org> on 2010/01/13 02:12:54 UTC

[jira] Commented: (MAHOUT-237) Map/Reduce Implementation of Document Vectorizer

    [ https://issues.apache.org/jira/browse/MAHOUT-237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12799508#action_12799508 ] 

Sean Owen commented on MAHOUT-237:
----------------------------------

I'll commit -- still seeing some code inspection warnings but we can look at it later.

> Map/Reduce Implementation of Document Vectorizer
> ------------------------------------------------
>
>                 Key: MAHOUT-237
>                 URL: https://issues.apache.org/jira/browse/MAHOUT-237
>             Project: Mahout
>          Issue Type: New Feature
>    Affects Versions: 0.3
>            Reporter: Robin Anil
>            Assignee: Robin Anil
>             Fix For: 0.3
>
>         Attachments: DictionaryVectorizer.patch, DictionaryVectorizer.patch, DictionaryVectorizer.patch, DictionaryVectorizer.patch, DictionaryVectorizer.patch, SparseVector-VIntWritable.patch
>
>
> Current Vectorizer uses Lucene Index to convert documents into SparseVectors
> Ted is working on a Hash based Vectorizer which can map features into Vectors of fixed size and sum it up to get the document Vector
> This is a pure bag-of-words based Vectorizer written in Map/Reduce. 
> The input document is in SequenceFile<Text,Text> . with key = docid, value = content
> First Map/Reduce over the document collection and generate the feature counts.
> Second Sequential pass reads the output of the map/reduce and converts them to SequenceFile<Text, LongWritable> where key=feature, value = unique id 
>     Second stage should create shards of features of a given split size
> Third Map/Reduce over the document collection, using each shard and create Partial(containing the features of the given shard) SparseVectors 
> Fourth Map/Reduce over partial shard, group by docid, create full document Vector

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