Thomas Walter wrote:
> pca = r.princomp(r.t(mat), cor=True)
>
> Okay, this works. But if I want to use the predict functionality of
> princomp, like:
> pred = r.predict(pca)
>
> I obtain the following error:
>
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> rpy.RException: Error in UseMethod("predict") : no applicable method for
> "predict"
>
> Does anybody know how I could deal with this problem?
This is because your 'pca' object in Python is not an R principal
components object. You need to mess with the conversion system:
>>> pca=r('princomp(USArrests)')
>>> pca
- a big hash/list object appears....
SO let's change the conversion mode:
>>> rpy.set_default_mode(rpy.NO_CONVERSION)
>>> pca=r('princomp(USArrests,cor=TRUE)')
>>> pca
<Robj object at 0xb7d493f0>
- now pca is a Robj this is basically the R object. So you can do:
>>> r.predict(pca)
but you get:
<Robj object at 0xb7d493e0>
which isn't very useful as is. You could reset the conversion mode, or
use r.print_(r.predict(pca)), which gives you the matrix.
Barry
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