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From Stuti Awasthi <>
Subject RE: Query about MatrixMultiplicationJob in Mahout
Date Fri, 11 Jan 2013 10:31:26 GMT
Also I have doubts in the way Matrix is submitted to map-reduce.
Lets Assume if my matrix is :
                1 2 3
                4 5 6
Then will Key be RowNumber and Value will be TupleValues ??? Something like this :

Key<IntWritable>            Value <TupleWritable>
    1                                                          1 2 3
    2                                                          4 5 6

Sorry for the basic questions but I am not able to find any useful links/docs

From: Stuti Awasthi
Sent: Friday, January 11, 2013 11:34 AM
Subject: Query about MatrixMultiplicationJob in Mahout

Hi All,
I am pretty new to Mahout and this is my first attempt . I wanted to tryout MatrixMultiplicationJob
but facing some issues in Input format.
I noticed that MatrixMultiplicationJob takes input as <IntWritable,TupleWritable> and
then perform the MR to produce matrix multiplication output in SequenceFileFormat<Intwritable,

So here I am at the first step to create the input file currently as TextInputFormat<LongWritable,Text>
to SequenceFileOutputFormat <IntWritable,TupleWritable>. So that I can send this type
of file as an input to MatrixMultiplicationJob

My Text input file is of format : Row = 2, Column = 3,
So I assume this will be picked as
1 2 3
4 5 6

This is the input file which I have created and not even sure if this is the correct way to
send input to convert the TextInputFormat to SequenceFile format.

Please Suggest


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