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From: Stuti Awasthi <stutiawasthi@hcl.com>
To: "user@mahout.apache.org" <user@mahout.apache.org>
Date: Mon, 14 Jan 2013 18:18:14 +0530
Subject: RE: MatrixMultiplicationJob Input query
Thread-Topic: MatrixMultiplicationJob Input query
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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 ma=
trix say 1millionX 1million.=20
For such large matrix, I was thinking to try the MatrixMultiplicationJob (M=
R 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]=20
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 multipl=
ication. 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 =3D 0;
        int m =3D 1;
        Vector vector =3D new SequentialAccessSparseVector(n);

        Matrix matrix =3D 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 =3D matrix.times(matrix);


        //Vector product =3D 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>=20
> --numColsA <Column no of MatrixA> --inputPathB <Inputpath of MatrixB> =20
> --numRowsB <Rowno of MatrixB> --numColsB <Column no of MatrixB>=20
> --tempDir <temporaryDir path>
>
> And getting the errors of InputFormat in mapper as mapper expects=20
> <TupleWritable> format. Now here Im not sure that what should be the=20
> 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=20
> > in input format. I want to create the input file of matrix in the=20
> > format which is required by MatrixMultiplicationJob for further=20
> > processing. Im facing issues in creating that file as I have doubts=20
> > that what will be the key and values for the input file. Anybody's=20
> > 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=20
> > few examples to guess the algorithm or browse source code.
> >
> > Regards,
> > Ashish
> >
> > On Mon, Jan 14, 2013 at 12:20 PM, Stuti Awasthi=20
> > <stutiawasthi@hcl.com
> > >wrote:
> >
> > > Hi,
> > > I want to execute MatrixMultiplicationJob provided in Mahout. I=20
> > > understand that the input file should be in SequenceFileFormat=20
> > > with input Key as IntWritable and Value as TupleWritable.
> > >
> > > If my matrix is  2x3 like :
> > >
> > > A =3D  1 2 3
> > >         4 5 6
> > >
> > > What should I keep as key and value in SequenceFileFormat so that=20
> > > I can provide it in MatrixMultiplicationJob as input. Sorry for=20
> > > the basic question but Im new to Mahout and not finding much=20
> > > details of MatrixMultiplicationJob execution.
> > >
> > > Thanks
> > > Stuti
> > >
> > >
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