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From Shirish Tatikonda <shirish.tatiko...@gmail.com>
Subject Re: Matrix Market format with metadata file
Date Tue, 16 Feb 2016 00:26:39 GMT
Both "mm" and "text" formats are identical except for a couple of
differences:

1) for "mm": the matrix metadata is included in the first two lines; and
for "text": the metadata is present in the associated .mtd file
2) "mm" data must be in a single file (i.e., no *part* files) where "text"
data can span multiple *part* files (like any other file on HDFS).

The support for "mm" is created mainly for the purpose of
importing/exporting data in the format that R likes.

Shirish

On Mon, Feb 15, 2016 at 4:17 PM, Deron Eriksson <deroneriksson@gmail.com>
wrote:

> Hi,
>
> I have a question with regards to text vs mm. Isn't the mm coordinate
> format identical to the text format but the mm data file happens to include
> the metadata line for rows, cols, and nnzs, so shouldn't they scale the
> same since the text row values (i,j,v) correspond to the mm rows?
>
> If we have the following MM:
> %%MatrixMarket matrix coordinate real general
> 4 3 6
> 1 1 1.0
> 1 2 2.0
> 1 3 3.0
> 3 1 7.0
> 3 2 8.0
> 3 3 9.0
>
> The corresponding text format (with accompanying metadata file) is:
> 1 1 1.0
> 1 2 2.0
> 1 3 3.0
> 3 1 7.0
> 3 2 8.0
> 3 3 9.0
>
> So aren't these formats essentially the same?
>
> Deron
>
>
> On Mon, Feb 15, 2016 at 3:56 PM, Matthias Boehm <mboehm@us.ibm.com> wrote:
>
> > The meta data file is still useful in order to get the format. In case of
> > matrix market, errors will be raised if included meta data is
> inconsistent.
> > So no, we should not disallow to specify the meta data. In general, we
> > anyway recommend using text (textcell) instead mm (matrix market) for
> > scalability reasons.
> >
> > Regards,
> > Matthias
> >
> > [image: Inactive hide details for Deron Eriksson ---02/15/2016 03:45:46
> > PM---Hi, The Matrix Market coordinate format contains # rows, #]Deron
> > Eriksson ---02/15/2016 03:45:46 PM---Hi, The Matrix Market coordinate
> > format contains # rows, # columns, and #
> >
> > From: Deron Eriksson <deroneriksson@gmail.com>
> > To: dev@systemml.incubator.apache.org
> > Date: 02/15/2016 03:45 PM
> > Subject: Matrix Market format with metadata file
> > ------------------------------
> >
> >
> >
> > Hi,
> >
> > The Matrix Market coordinate format contains # rows, # columns, and #
> > non-zero values as metadata near the top of a matrix data file.
> >
> > If I write a matrix in mm format using SystemML, no metadata file is
> > created since the metadata is stored within the data file.
> >
> > However, when reading a matrix with mm format, I can supply a metadata
> > file, even though metadata exists in the matrix data file. Is there any
> > reason for this, or should this be disallowed since the metadata file is
> > redundant and can cause confusion, since metadata values can then be
> > specified in two places, which then brings up the question, "which
> metadata
> > value should be used"?
> >
> > Deron
> >
> >
> >
>

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