[Tutor] Python and rpy

Kent Johnson kent37 at tds.net
Mon Dec 25 03:05:20 CET 2006

Geoframer wrote:

> As i stated i think the conversion from Python to R is going wrong, but 
> i have no clue on how to properly address that.

I agree. If you have Numeric installed (which I do) then r.diag() should 
return a Numeric array, not a list of lists. This looks like the same 
problem discussed in this thread:
which does not seem to have been resolved.

I don't want to get involved in the Rpy mailing list but I would suggest 
posting a very simple question asking why the result of r.diag() is not 
a Numeric array. Perhaps this will lead to a solution.

> The code snippet i was talking about is on page 15 and 16 of the rpy 
> reference guide http://rpy.sourceforge.net/rpy/doc/rpy.pdf ; the 
> examples just don't work and i am lacking enough python experience to 
> see why :-S.
> What i'm trying to do now is :
> ----
> from rpy import *
> class Test:
>     def as_r(self):
>         return [[1,2,3,4,5],[2,3,4,5,1],[3,4,5,1,2],[4,5,1,2,3],[5,1,2,3,4]]
> if __name__ == "__main__":
>     a=with_mode(NO_CONVERSION, Test)()
>     r.kmeans(a, 2, 5, 10, "Forgy")

I don't see how this will help. My understanding is that as_r() should 
return an Robj, not a Python object. I think this code is the same as 
passing a list of lists directly to kmeans.


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