[R] the secret (?) language of lists

Berton Gunter gunter.berton at gene.com
Wed Nov 15 00:43:47 CET 2006


Peter Dalgaard wrote:

There are a few basic principles in play here, once you know them, the
rest follows; I'm not sure exactly where they are documented, but I'd
guess at Venables & Ripley's books (MASS, S Programming) at least, the
"Blue Book" on S, and possibly others.

The first suggestion requires that you know or now about the following

- matrices are vectors with dim attibutes, stored column-major

** This is clearly documented in AN Introduction to R

— binding rows into matrices with rbind()

** Documented in rbind's Help file.

- c() removes attributes

** Documented in c()'s Help file

The second one requires

- rep function, and its each=

** Documented in rep's Help file

- vector recycling in arithmetic
** Documented in Introduction to R and many Help files

So, in fact, one does not need to go so far as MASS or S Programming -- or
heaven forfend! -- the Blue Book. Indeed I learned about all of this by just
reading the basic stuff before I even knew about these other (excellent and
valuable, I grant) resources. Of course, cleverness in using R's
well-documented capabilities is never guaranteed, but it is important to
recognize that one need not hunt for the docs: they're where they should be.


Which, I regret to say, leads me to echo Brian Ripley's pungent plea:

install.packages("fortunes"); library(fortunes); fortune("WTFM")

Cheers,
Bert Gunter 

 
> I am reminded of quote by Byron Ellis: "Contrary to popular belief  
> the speed of R's interpreter is rarely the limiting factor to R's  
> speed. People treating R like C is typically the limiting factor. You  
> have vector operations, USE THEM."  Not exactly the point, but close.
> 
> Thanks!
> 
> Jeff Spies
> http://www.nd.edu/~jspies/
> 
> 
> 	[[alternative HTML version deleted]]
> 
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-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907

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