I found two minor differences when porting some S-plus code to R (the code
was written for Splus 3.5 Unix).
(1) The function c(), when applied to a name and a character, under S-plus
coerces the name to character data and returns a vector of character data,
but in R returns a list containing both objects intact
(2) The call match.call(expand.dots=F) returns an object that behaves
differently: under S-plus it is a call object with a "list" functor,
under
R it is an ordinary list with no "list" functor. (e.g.,
as.character(match.call(expand.dots=F)$...) under S-plus has
length(list(...))+1 elements, of which the first is "list", but under
R it
has just length(list(...)) elements)
Example of (1)
under R (both 1.5 and 1.4.1):
> c("foo", as.name("bar"))
[[1]]
[1] "foo"
[[2]]
bar
under S-plus 6.0 (and earlier, I believe)
> c("foo", as.name("bar"))
[1] "foo" "bar"
[I would agree that it is unclear what the most desirable behavior is, and
would also agree that clean code would do an as.character() on a name
before attempting to concatenate it with character data - I changed my code
to do this.]
Example of (2)
Under R 1.4.1:
> (function(...)browser())(x=1,y=2)
Called from: (function(...) browser())(x = 1, y = 2)
Browse[1]> match.call(expand.dots=F)
(function(...) browser())(... = list(x = 1, y = 2))
Browse[1]> match.call(expand.dots=F)$...
$x
[1] 1
$y
[1] 2
Browse[1]> is.call(match.call(expand.dots=F)$...)
[1] FALSE
Browse[1]> names(match.call(expand.dots=F)$...)
[1] "x" "y"
Browse[1]> as.character(match.call(expand.dots=F)$...)
[1] "1" "2"
Under S-plus 6.0:
> (function(...)browser())(x=1,y=2)
Called from: (function(...) browser())....
b()> match.call(expand.dots=F)
(function(...)
browser())(... = list(x = 1, y = 2))
b()> match.call(expand.dots=F)$...
list(x = 1, y = 2)
b()> is.call(match.call(expand.dots=F)$...)
[1] T
b()> names(match.call(expand.dots=F)$...)
[1] "" "x" "y"
b()> as.character(match.call(expand.dots=F)$...)
[1] "list" "1" "2"
(Feel free to let me know whether or not minor incompatibilities like this
are of interest to the R-developers -- I don't know to what degree people
are trying to make R compatible with S-plus.)
-- Tony Plate
> version
_
platform i386-pc-mingw32
arch x86
os Win32
system x86, Win32
status
major 1
minor 4.1
year 2002
month 01
day 30
language R
>
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