Python

You don't need to get any book, just read the online chapters one by one on its official website:-
https://docs.python.org/2/tutorial/index.html

It is mainly used for server side programming. Its framework Django efficiently uses MVC structure. Moreover it's a scripting language so it's very flexible writing server side code.

You don't need to get any book, just read the online chapters one by one on its official website:-
https://docs.python.org/2/tutorial/index.html

R is used more for data analysis.

Hi
Mentioned below are some of the books that you can consider :
Python by Mike McGrath
Data Structure and Algorithmic Thinking with Python
by Narasimha Karumanchi
Head First Python by Paul Barry
Learning Python: Powerful Object-Oriented Programming: 5th Edition
by Mark Lutz
All the best

Hi Tom,
Listed below are some of the weaknesses of python:
Performance is the main issue. When it comes down to optimized code with demands of high speed, Python is not an efficient solution.
No compile-time type-checks :You cannot know if you've created a type error until it happens in run time.
All the best

Hi Tom,
Python is one of the most widely adopted general-purpose modern scripting-languages. (Javascript is used more by pure volume, but is fairly rare for anything other than webpages) It seems a pretty safe bet that Python is here to stay over the next decade.
All the best

Hi Tom,
Both are good, what i will suggest is learn how they inter-operate together. Start with one and then add the other to your workflow.
All the best

Hi Tom,
Mentioned below are some of the advantages of python over ruby:
1. Easier to read
2. Tons of libraries
3. Community
4. Practicality - popular for many uses besides web development
All the best

I would like to invite Jimmy Bikram to share his views