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From Stuti Awasthi <stutiawas...@hcl.com>
Subject RE: MatrixMultiplicationJob Input query
Date Mon, 14 Jan 2013 12:48:14 GMT
Hi Ashish,

Thanks for the response. The code snippet you gave certainly worked for the matrix multiplication.
But in my usecase the matrix will be large dense matrix say 1millionX 1million. 
For such large matrix, I was thinking to try the MatrixMultiplicationJob (MR job) provided
by Mahout and if I can use this for such dense distributed matrix and check the performance
also.

Thanks

-----Original Message-----
From: ashish negi [mailto:ashishnegioffice@gmail.com] 
Sent: Monday, January 14, 2013 5:33 PM
To: user@mahout.apache.org
Subject: Re: MatrixMultiplicationJob Input query

Hi,

I'll try as you said meanwhile following is how I prototyped matrix multiplication. Hope it'll
satisfy your matrix multiplication need.
------
import org.apache.mahout.math.Matrix;
import org.apache.mahout.math.SequentialAccessSparseVector;
import org.apache.mahout.math.SparseMatrix;
import org.apache.mahout.math.Vector;


public class MatrixMult {

    public static void main(String[] args) {

        int n = 0;
        int m = 1;
        Vector vector = new SequentialAccessSparseVector(n);

        Matrix matrix = new SparseMatrix(2,2);//(new int[] {2, 2});

        matrix.set(0, new double[]{2.0,2.0});
        matrix.set(1, new double[]{2.0,2.0});

        Matrix productMatrix = matrix.times(matrix);


        //Vector product = productMatrix.getColumn(0);

    }

}

Regards,

On Mon, Jan 14, 2013 at 4:05 PM, Stuti Awasthi <stutiawasthi@hcl.com> wrote:

> Hi Ashish,
>
> Im running the job like this :
>
> mahout matrixmult --inputPathA  --numRowsA <Rowno of MatrixA> 
> --numColsA <Column no of MatrixA> --inputPathB <Inputpath of MatrixB>  
> --numRowsB <Rowno of MatrixB> --numColsB <Column no of MatrixB> 
> --tempDir <temporaryDir path>
>
> And getting the errors of InputFormat in mapper as mapper expects 
> <TupleWritable> format. Now here Im not sure that what should be the 
> keys  and Value<TupleWritable> as Input to mapper to get this job working.
>
> -Stuti
>
>
> -----Original Message-----
> From: ashish negi [mailto:ashishnegioffice@gmail.com]
> Sent: Monday, January 14, 2013 2:29 PM
> To: user@mahout.apache.org
> Subject: Re: MatrixMultiplicationJob Input query
>
> Could you tell how are you trying to run the job?
>
> Regards,
>
> On Mon, Jan 14, 2013 at 1:42 PM, Stuti Awasthi <stutiawasthi@hcl.com>
> wrote:
>
> > Hi Ashish,
> > I tried to run the "matrixmult" example of Mahout but getting errors 
> > in input format. I want to create the input file of matrix in the 
> > format which is required by MatrixMultiplicationJob for further 
> > processing. Im facing issues in creating that file as I have doubts 
> > that what will be the key and values for the input file. Anybody's 
> > help
> will be appreciated.
> >
> > Thanks
> > Stuti
> >
> > -----Original Message-----
> > From: ashish negi [mailto:ashishnegioffice@gmail.com]
> > Sent: Monday, January 14, 2013 1:04 PM
> > To: user@mahout.apache.org
> > Subject: Re: MatrixMultiplicationJob Input query
> >
> > Hi Stuti,
> >
> > I am not with specific answer of your question but why don't you try 
> > few examples to guess the algorithm or browse source code.
> >
> > Regards,
> > Ashish
> >
> > On Mon, Jan 14, 2013 at 12:20 PM, Stuti Awasthi 
> > <stutiawasthi@hcl.com
> > >wrote:
> >
> > > Hi,
> > > I want to execute MatrixMultiplicationJob provided in Mahout. I 
> > > understand that the input file should be in SequenceFileFormat 
> > > with input Key as IntWritable and Value as TupleWritable.
> > >
> > > If my matrix is  2x3 like :
> > >
> > > A =  1 2 3
> > >         4 5 6
> > >
> > > What should I keep as key and value in SequenceFileFormat so that 
> > > I can provide it in MatrixMultiplicationJob as input. Sorry for 
> > > the basic question but Im new to Mahout and not finding much 
> > > details of MatrixMultiplicationJob execution.
> > >
> > > Thanks
> > > Stuti
> > >
> > >
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