I see a many times in job description for data scientist asking for Python/Java experience and disregard R. Below is a personal email I received from chief data scientist of a company I applied for through linkedin.
X, Thanks for connecting and expressing interest. You do have good Analytics Skills. However, all our data scientists must have good programming skills in Java/Python as we are a internet/mobile organisation and everything we do is online.
While I respect the decision of the chief data scientist, I am unable to get a clear picture as to what are the tasks that Python can do that R cannot do. Can anyone care to elaborate? I am actually keen to learn Python/Java, provided I get a bit more detail.
Edit: I found an interesting discussion on Quora. Why is Python a language of choice for data scientists?
Edit2: Blog from Udacity on Languages and Libraries for Machine Learning