Converting python objects for rpy2
You need to add
import rpy2.robjects.numpy2rirpy2.robjects.numpy2ri.activate()See more in rpy2 documentation numpy section (here for the older 2.x version)
Prior to 2.2.x the import alone was sufficient.
That import alone is sufficient to switch an automatic conversion of numpy objects into rpy2 objects.
Why make this an optional import, while it could have been included in the function py2ri() (as done in the original patch submitted for that function) ?
Although both are valid and reasonable options, the design decision was taken in order to decouple rpy2 from numpy the most, and do not assume that having numpy installed automatically meant that a programmer wanted to use it.
For me (2.2.1) the following also worked (as documented on http://rpy.sourceforge.net/rpy2/doc-2.2/html/numpy.html):
import rpy2.robjects as rofrom rpy2.robjects.numpy2ri import numpy2riro.conversion.py2ri = numpy2ri