Gregor:
Works for me on 2.3.0:
> mapply(function(x,y,z) paste(y,z), letters,as.list(LETTERS),as.list(1:26))[
> 1:5 ]
a b c d e
"A 1" "B 2" "C 3" "D 4" "E 5"
> mapply(function(x,y,z) paste(x,y,z), letters,as.list(LETTERS),as.list(1:26))[
> 1:5 ]
a b c d e
"a A 1" "b B 2" "c C 3" "d D 4" "e E 5"
>
but this does not yield names:
> mapply(function(x,y,z) paste(x,y,z),
> as.list(letters),as.list(LETTERS),as.list(1:26))[ 1:5 ]
[1] "a A 1" "b B 2" "c C 3" "d D 4" "e E 5"
Perhaps the help page would be clearer if it said:
USE.NAMES: If the first ... argument is a character ***vector*** and the result
doesn't already have names, use it as the names
Chuck
On Thu, 31 Aug 2006, Gregor Gorjanc wrote:
> Hello!
>
> I have noticed that mapply() drops names in R 2.3.1 as well as in
> r-devel. Here is a simple example:
>
> l <- list(a=1, b=2)
> k <- list(1)
> mapply(FUN="+", l, k)
> [1] 2 3
> mapply(FUN="+", l, k, SIMPLIFY=FALSE)
> [[1]]
> [1] 2
>
> [[2]]
> [1] 3
>
> Help page does not indicate that this should happen. Argument USE.NAMES
> does not have any effect here as it used only in a bit special
> situation: "If the first ... argument is character and the result does
> not already have names, use it as the names." But result is always
> without names as shown above. Did I miss any peculiarities?
>
> This is not consistent with lapply, which keeps names i.e.
>
> lapply(l, "+", 1)
> $a
> [1] 2
>
> $b
> [1] 3
>
> I have attached and copied (at the end) patch proposal against SVN that
> adds names back to the result if x had it (only R as my C is ...). This
> way it would also be consistent with lapply. make check-all seems to be
> happy with changes. Now we get:
>
> mapply(FUN="+", l, k)
> a b
> 2 3
>
> mapply(FUN="+", l, k, SIMPLIFY=FALSE)
> $a
> [1] 2
>
> $b
> [1] 3
>
> And if we had "character" (with some variations) for first ... then:
>
> l <- list(a="1", b="2")
> mapply(FUN="paste", l, k)
> a b
> "1 1" "2 1"
>
> l <- list("1", "2")
> mapply(FUN="paste", l, k)
> [1] "1 1" "2 1"
>
> l <- c("1", "2")
> mapply(FUN="paste", l, k)
> 1 2
> "1 1" "2 1"
>
> Index: src/library/base/R/mapply.R
> ===================================================================
> --- src/library/base/R/mapply.R (revision 39024)
> +++ src/library/base/R/mapply.R (working copy)
> @@ -3,8 +3,16 @@
> FUN <- match.fun(FUN)
> dots <- list(...)
>
> + if(!is.null(names(dots[[1]]))) {
> + isNamed <- TRUE
> + namesX <- names(dots[[1]])
> + } else {
> + isNamed <- FALSE
> + }
> +
> answer<-.Call("do_mapply", FUN, dots, MoreArgs, environment(),
> PACKAGE="base")
> + if(isNamed) names(answer) <- namesX
>
> if (USE.NAMES && length(dots) && is.character(dots[[1]]) &&
> is.null(names(answer))) names(answer) <- dots[[1]]
> @@ -47,4 +55,4 @@
> }
> formals(FUNV) <- formals(FUN)
> FUNV
> -}
> \ No newline at end of file
> +}
>
> --
> Lep pozdrav / With regards,
> Gregor Gorjanc
>
> ----------------------------------------------------------------------
> University of Ljubljana PhD student
> Biotechnical Faculty
> Zootechnical Department URI: http://www.bfro.uni-lj.si/MR/ggorjan
> Groblje 3 mail: gregor.gorjanc <at> bfro.uni-lj.si
>
> SI-1230 Domzale tel: +386 (0)1 72 17 861
> Slovenia, Europe fax: +386 (0)1 72 17 888
>
> ----------------------------------------------------------------------
> "One must learn by doing the thing; for though you think you know it,
> you have no certainty until you try." Sophocles ~ 450 B.C.
> ----------------------------------------------------------------------
>
Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:[EMAIL PROTECTED] UC San Diego
http://biostat.ucsd.edu/~cberry/ La Jolla, San Diego 92093-0717
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