[rkward-devel] New plugin and functions

[Thomas Friedrichsmeier]

On Thursday 19 April 2007 14:59, I. Soumpasis wrote:
> > 1) The barplot functionality should be made an embedded plugin so the
> > code can
> > be shared between the standalone barplot and this one. If you don't know
> > how
> > to approach this, I can take a look, later, but if you have the time to
> > look
> > at this, that would certainly be good.
>
> That was my thought in the first place but did not know how to do it and I
> was in great harry to get results for the data I had.

Ok, I'll look at it soon.

> 3) Perhaps the most basic: table() will happily take any number of
>
> > arguments.
[...]

> Here are my thoughts. (Limited responsibility, because there is some time
> passed since I wrote it nd I do not remember all the things I thought then
> plus I do not have an SPSS right now).
> 1. A small problem we have to see. If we use more than two variables the
> format of the result changes. As I remember of the SPSS crosstabulation
> they have one dependent and many independent variables. In this way we
> could crosstabulate the dependent with each independent and then put them
> in a table. Do you find this a sound solution?

I don't think table() has the notion of dependent and independent variables at 
all. It simply generates all combinations of levels, and then counts, how 
often those occur. xtabs() can do the same, or alternatively sum up the 
values in an additional field (which will typically already contain counts). 
Is that what you had in mind?

I think the output format is something to worry about last. rk.print() will 
already handle 3+ dimensional tables, and in light of the next issues, we may 
have to break up the table for 3 or more dimensions, anyway. I'd say, for 
now, let's think about what would be nice, without worrying too much about 
the details.

> 2. SPSS also does one barplot for every crosstabulation. With the above
> solution is easiest to be done for ever pair dependent-independent we have.
> The only minus is that we have to stop offering preview, something  logical
> because here we have an analysis, not a plotting plugin.

We could still offer a preview for the first table (ok, now I am slightly 
worried about how to code this, but it should be doable).

> 3. Same with chisquare test.

Yes, this would need to be calculated for each 2 dimensional slice, 
separately.

On the other hand, the easy route for those two would be to simply offer this 
(and the barplot) functionality if - and only if - there are only two 
variables. It might be good enough for now, and could perhaps be extended, 
later, if we see a good way to do it.

> Yes you are right, but I will wait for what we are finally going to do with
> the whole plugin.

Good point.

Regards
Thomas
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