The data is from Freebase http://www.freebase.com/view/computer/programming_language http://www.freebase.com/view/computer/programming_language and the code to

The data is from Freebase http://www.freebase.com/view/computer/programming_language http://www.freebase.com/view/computer/programming_language and the code to get the data is in this GitHub repo https://github.com/exploringdata/programming-languages-influence https://github.com/exploringdata/programming-languages-influ.... From Wikipedia's R page: "R is an implementation of the S programming language combined with lexical scoping semantics inspired by Scheme." Guess that explains it.