ivo...@gmail.com wrote:
> Gentlemen---these are all very clever workarounds, but please forgive me
> for voicing my own opinion: IMHO, returning multiple values in a
> statistical language should really be part of the language itself. there
> should be a standard syntax of some sort, whatever it may be, that everyone
> should be able to use and which easily transfers from one local computer to
> another. It should not rely on clever hacks in the .Rprofile that are
> different from user to user, and which leave a reader of end user R code
> baffled at first by all the magic that is going on. Even the R tutorials
> for beginners should show a multiple-value return example right at the
> point where function calls and return values are first explained.
>
>
hi again,
i was playing a bit with the idea of multiple assignment, and came up
with a simple codebit [1] that redefines the operator '='. it hasn't
been extensively tested and is by no means foolproof, but allows various
sorts of tricks with multiple assignments:
source('http://miscell.googlecode.com/svn/rvalues/rvalues.r',
local=TRUE)
a = function(n) 1:n
# a is a function
b = a(3)
# b is c(1, 2, 3)
c(c, d) = a(1)
# c is 1, d is NULL
c(a, b) = list(b, a)
# swap: a is 1:3, b is a function
# these are equivalent:
c(a, b) = 1:2
{a; b} = 1:2
list(a, b) = 1:2
a = data.frame(x=1:3, y=3)
# a is a 2-column data frame
c(a, b) = data.frame(x=1:3, b=3)
# a is c(1, 2, 3), b is c(3, 3, 3)
and so on. this is sort of pattern matching as in some functional
languages, but only sort of: it does not do recursive matching, for
example:
c(c(a, b), c) = list(1:2, 3)
# error
# not: a = 1, b = 2, c = 3
anyway, it's just a toy for which there is no need.
vQ
[1] svn checkout */http/*://miscell.googlecode.com/svn/rvalues
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
