出于教学目的，什么是真正干净和清晰的[R]代码的好例子？

I'm working with a small team of analysts and statisticians on what will be a medium-sized body of R code. They're smart people, but they're not trained or experienced as programmers, per se. (I am.) They've written some R code, but for our project to be expandable, efficient, and maintainable, it needs to become well-structured, and rather more piratical. One of the better way to learn to be a better programmer is to study elegant existing code. Can anyone suggest some open source examples of R code (on CRAN or wherever) that you think are particularly clear, literate, and good examples? Functional is good, S3 objects are OK, deep magic is bad. I'm working with a small team of analysts and s