import pandas
import numpy
import scipy

import rpy2
from rpy2.robjects import r
from collections import OrderedDict
py2ri_orig = rpy2.robjects.conversion.py2ri
def conversion_pydataframe(obj):
    print "CONVERTING TO PYDATAFRAME"
    if isinstance(obj, pandas.core.frame.DataFrame):
        od = OrderedDict()
        for name, values in obj.iteritems():
            if values.dtype.kind == 'O':
                od[name] = rpy2.robjects.vectors.StrVector(values)
            else:
                od[name] = rpy2.robjects.conversion.py2ri(values)
        return rpy2.robjects.vectors.DataFrame(od)
    else:
        return py2ri_orig(obj)

rpy2.robjects.conversion.py2ri = conversion_pydataframe


df = pandas.DataFrame({"a": 1, "b": 2},
                       {"c": 3, "d": 4})
print type(df)
r.plot(df)


Yields the error:


<class 'pandas.core.frame.DataFrame'>
CONVERTING TO PYDATAFRAME
CONVERTING TO PYDATAFRAME
Traceback (most recent call last):

rpy2/robjects/__init__.py", line 144, in default_py2ri
    raise(ValueError("Nothing can be done for the type %s at the moment." %(type(o))))
ValueError: Nothing can be done for the type <class 'pandas.core.series.Series'> at the moment.