[RkWard-devel] Scatterplot Matrix

[Thomas Friedrichsmeier]

Hi Ilias,

On Monday 15 January 2007 14:16, I. Soumpasis wrote:
> I made one more chart that I had in mind.
>
> It is a scatterplot matrix that can be used with matrices or dataframes, or
> with variables from a dataframe or matrix. The function is
> scatterplot.matrix from package car. It combines a scatterplot with
> "density", "boxplot", "histogram", "oned", "qqplot" or no plot at the
> diagonal panel. It can be used for a full picture of data, as correlation
> graph.
>
> The user can choose which graph to produce, if he wants points to be
> ploted, smooth, or ellipses at the 0.5 and 0.9 (normal) probability or
> confidence levels.
>
> I hope there are no problems in this graph and I learned from the previous
> one.

yes, it's getting harder to find something to improve! Here's what I found 
(since all of this was small stuff, I've done already done in in SVN):
- Small copy and paste bug: rk.header ("Correlation Matrix Plot")
- File naming: I renamed the files to scatterplot_matrix.php/xml. No need to 
save a few characters, here, and this way it's easier for someone working on 
the plugins to discern what the files are all about.
- Removed a few spaces and newlines. Purely aesthetic, and not exactly 
important.
- Added a try statement around the plot itself (remember, this is a good idea 
for everything between rk.graph.on (), and rk.graph.off ())
See 
http://rkward.svn.sourceforge.net/viewvc/rkward/trunk/rkward/rkward/plugins/plots/ .

Another thing that you *could* do, if you like:
- Most parameters have a default value in scatterplot.matrix (). E.g., 
specifying smooth=TRUE is not strictly needed, as that is already the default 
setting. As is, it's probably ok, or even nice, to print this anyway, but if 
you ever add GUI options for some of the other parameters of 
scatterplot.matrix (), the generated code might easily become tedious to 
read. In this case, you'd try to avoid specifying the default values.
For a checkbox option, this is very easy to accomplish. Instead of writing:

<checkbox id="smooth" value="TRUE" value_unchecked="FALSE" [...]/>
and
scatterplot.matrix([...], smooth=<? getRK ("smooth"); ?>)

you could write:

<checkbox id="smooth" value=", smooth=TRUE" value_unchecked="" [...]/>
and
scatterplot.matrix([...]<? getRK ("smooth"); ?>)

Well, again, this is optional, and maybe not even a good idea as long as there 
are only four or five options.

> Any suggestions appreciated. I hope you like it.

Very nice. Thanks!

> If there are all ok with this graph, I would like to write the help pages
> for these two graphs. So what should I do? Write rkh pages? A little
> guidance would be appreciated.

There is a new section on this in the writing plugins documentation:
http://rkward.sourceforge.net/documents/devel/plugins/pluginhelp.html

I hope to have included all the relevant details, but write back, if something 
is missing or unclear. The only example of a plugin with a help page 
is "Descriptive Statistics", so far (directory plugins/descriptive/). I hope 
it shows everything you will need.

Regards
Thomas
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