[R] ggplot2 and lattice

[Claudia Beleites]

Am Dienstag 16 Dezember 2008 17:13:33 schrieb Wayne F:
> stephen sefick wrote:
> > yes a parallel coordinates plot- I understand that it is for
> > multivariate data, but I am having a hard time figuring out what it is
> > telling me.  Thanks for your help.
>
> In the lattice book, the author mentions that static parallel plots aren't
> very useful, in general.
While for some data they are just natural: e.g. when spectra are treated as 
multidimensional data. Then the parallel coordinate plot just gives you the 
spectrum. 
Of course, in this situation it is maybe the treatment as high-dimensional 
data that is somewhat weird for spectra. 

However, this offers a way, that might help understanding what's going on. 

I have a data set of p dimensions. E.g. spectra measured with p channels.
Now, we can either think of such a spectrum as a point in p-d. E.g. a spectrum 
consisting of red, green, blue intensity is at a certain point in rgb-space.

On the other hand, here the p dimensions have something to do with each other 
(e.g. an intrinsic order, let's say, by the wavelength). So it does make sense 
to plot the intensity over the p dimensions. That's the parallel coordinate 
plot. 

What you can tell from such a plot, depends very much on your data, and how 
you treated it. 

Claudia



-- 
Claudia Beleites
Dipartimento dei Materiali e delle Risorse Naturali
Università degli Studi di Trieste
Via Alfonso Valerio 6/a
I-34127 Trieste

phone: +39 (0 40) 5 58-34 47
email: cbeleites at units.it