R can legitimately be called both a programming language and a statistical package. Many books address both the programming and statistical components of R, but invariably the discussion of statistical topics is more detailed than the discussion of programming capabilities. As a supplement, I’ve started the list of links below. Each of these sources deals specifically and almost exclusively with the the programming aspects of R: objects, arrays, loops and conditional statements, custom functions, debugging, and so on. I’ll add to this list as I become aware of other sites. Please feel free to suggest additional sites in the comments.
- Programming in R
- Programming in R II (same title, but different content)
- R language definition (html)
- R language definition (pdf)
- Writing R Extensions
- R Internals
- R Inferno
For a list of complementary sites that focus on statistical principles and research methods (several deal specifically with R) read this article.
Apart from all other programming languages R is one of the rare and unique programming language ever, it is knonw as statistical package also, therefore these are being used in developing statistical packages and varieties of graphical techniques, really we are still aware of this programming language which deserves the best as compare to other programming language.