There are a few ways to do this, but the only one that worked for me was to use Rserve and rconnect. In R, do this:
install.packages("Rserve")
library(Rserve)
Rserve(debug = FALSE, port=6311, args=NULL)
Then you can connect in Python very easily. Here is a test in Python:
rcmd = pyRserve.rconnect(host='localhost', port=6311)
print(rcmd('rnorm(100)'))