On Tue, Feb 15, 2011 at 1:04 PM, Paul Johnson <pauljoh...@gmail.com> wrote: > Hello, > > I am looking for CRAN packages that don't teach bad habits. Can I > have suggestions? > > I don't mean the recommended packages that come with R, I mean the > contributed ones. I've been sampling a lot of examples and am > surprised that many ignore seemingly agreed-upon principles of R > coding. In r-devel, almost everyone seems to support the "functional > programming" theme in Chambers's book on Software For Data Analysis, > but when I go look at randomly selected packages, programmers don't > follow that advice. > > In particular: > > 1. Functions must avoid "mystery variables from nowhere." > > Consider a function's code, it should not be necessary to say "what's > variable X?" and go hunting in the commands that lead up to the > function call. If X is used in the function, it should be in a named > argument, or extracted from one of the named arguments. People who > rely on variables floating around in the user's environment are > creating hard-to-find bugs. > > 2. We don't want functions with indirect effects (no <<- ), almost always. > > 3. Code should be vectorized where possible, C style for loops over > vector members should be avoided. > > 4. We don't want gratuitous use of "return" at the end of functions. > Why do people still do that? > > 5. Neatness counts. Code should look nice! Check out how beautiful > the functions in MASS look! I want code with spaces and " <- " rather > than everything jammed together with "=". > > I don't mean to criticize any particular person's code in raising this > point. For teaching exemples, where to focus? > > Here's one candidate I've found: > > MNP. as far as I can tell, it meets the first 4 requirements. And it > has some very clear C code with it as well. I'm only hesitant there > because I'm not entirely sure that a package's C code should introduce > its own functions for handling vectors and matrices, when some general > purpose library might be more desirable. But that's a small point, > and clarity and completeness counts a great deal in my opinion. >
There was some discussion of this on stats stackexchange http://stats.stackexchange.com/questions/5418/first-r-packages-source-code-to-study-in-preparation-for-writing-own-package -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
