I have been programming python too long to make an objective comparison with R. I have had to use R libraries at times, and I've found rpy to be a workable bridge from R to python for this purpose. Depending on how it works under the hood, it might not be appropriate for big data, though. Also, I had to custom modify some R libraries to work with my data, so it has been useful to know a bit of both, although I mostly picked up the R as I did the mods.