R help - Apr 2006 - PCA biplot question

Hi everyone,
I'd like to project two pcas onto one device window.  
 
I plot my first PCA:
biplot(prcomp(t(cerebdevmat)), var.axes=FALSE, cex=c(1,.1),
pc.biplot=TRUE)
 
Now I'd like to project the features of another PCA onto this graph.
 
Any suggestions?
 
I know this is easily done in MatLab but haven't figured it out in R.
 
Thanks,
Tanya

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I think you're asking how to plot arrows for variables in one dataset 
onto the PCA plot for another dataset? You can do this with functions 
from the vegan package. Particularly, vector and factor fitting can be 
done with envfit() and surface fitting with ordisurf().

There's a good tutorial at:

http://cc.oulu.fi/~jarioksa/softhelp/vegan.html

Cheers,

Tyler

Hi, hi all,
> Hi everyone,
> I'd like to project two pcas onto one device window.
> I plot my first PCA:
> biplot(prcomp(t(cerebdevmat)), var.axes=FALSE, cex=c(1,.1),
> pc.biplot=TRUE)
> Now I'd like to project the features of another PCA onto this graph.
> Any suggestions?
You can used co-inertia analysis (coinertia in package ade4)
or maybe procuste  analysis (package vegan, ade4, shapes)
these analyses are adapted to the simultaneous analyses of two tables.

cheers,


Pierre



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