I am writing a new book on a new language for me (python) for a new publisher ( Wiley)
This book is the first of its kind to provide a reference that enables students and practitioners to easily learn to code in Python if they are familiar with R and vice versa, even if they are beginners in the second language. It also provides a detailed introduction and overview of each language to the reader who might be unfamiliar with the other. While R has better statistical and graphical tools, Python has good machine learning tools and proves to be more useful software for the analysis of Big Data. A unique feature of this book is how it provides a command-by-command translation between R and Python for many mathematical, visualization and machine learning techniques. The intended audience is statistical practitioners and data scientists trying to learn one of R or Python or both, as well as students that are familiar with one of the languages.
http://www.amazon.co.uk/Python-R-Users-Ajay-Ohri/dp/1119126762