Tips for golfing in R I'm looking for tips for golfing in the R statistical language.  R is perhaps an unconventional choice for Golf.  However, it does certain things very compactly (sequences, randomness, vectors, and lists), many of the built-in functions have very short names, and it has an optional line terminator (;).  What tips and tricks can you give to help solve code golf problems in R?
Some tips:


In R, it's recommended to use &lt;- over =. For golfing, the
opposite holds since = is shorter...
If you call a function more than once, it is often beneficial to
define a short alias for it:

as.numeric(x)+as.numeric(y)

a=as.numeric;a(x)+a(y)

Partial matching can be your friend, especially when functions
    return lists which you only need one item of.  Compare
    rle(x)$lengths to rle(x)$l
Many challenges require you to read input. scan is often a good fit for this (the user ends the input by entring an empty line).

scan()    # reads numbers into a vector
scan(,'') # reads strings into a vector

Coercion can be useful.  t=1 is much shorter than t=TRUE.  Alternatively, switch can save you precious characters as well, but you'll want to use 1,2 rather than 0,1.

if(length(x)) {} # TRUE if length != 0
sum(x&lt;3)         # Adds all the TRUE:s (count TRUE)

If a function computes something complicated and you need various other types of calculations based on the same core value, it is often beneficial to either: a) break it up into smaller functions, b) return all the results you need as a list, or c) have it return different types of values depending on an argument to the function.
As in any language, know it well - R has thousands of functions, there is probably some that can solve the problem in very few characters - the trick is to know which ones!


Some obscure but useful functions:

sequence
diff
rle
embed
gl # Like rep(seq(),each=...) but returns a factor


Some built-in data sets and symbols:

letters     # 'a','b','c'...
LETTERS     # 'A','B','C'...
month.abb   # 'Jan','Feb'...
month.name  # 'January','Feburary'...
T           # TRUE
F           # FALSE
pi          # 3.14...