Re: [Rd] Aliasing a function
Dear Hadley, Why not just f <- g ? Regards, John John Fox, Professor Department of Sociology McMaster University Hamilton, Ontario, Canada L8S 4M4 905-525-9140x23604 http://socserv.mcmaster.ca/jfox > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > project.org] On Behalf Of hadley wickham > Sent: February-23-08 5:40 PM > To: R-devel > Subject: [Rd] Aliasing a function > > A simple way to alias a function is to do : > > g <- function(a = 1, b = 2, c = 3) a + b * c > f <- function(...) g(...) > > but formals (etc) is no longer very helpful. Is there an easy way to > programmatically create: > > f <- function(a=1, b=2, c=3) g(a=a, b=b, c=c) > > This comes up in ggplot2 where I alias many functions to hide the fact > that I'm using proto in the background, and I'd like the aliased > functions to be a little more user friendly in terms of revealing what > are valid arguments (and also to match up with the rdoc files which I > am building). > > Any ideas? > > Thanks, > > Hadley > > -- > http://had.co.nz/ > > __ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] Aliasing a function
formals can be used like this: f <- g formals(f) <- pairlist(a=1,b=2,c=3) On Sat, Feb 23, 2008 at 5:40 PM, hadley wickham <[EMAIL PROTECTED]> wrote: > A simple way to alias a function is to do : > > g <- function(a = 1, b = 2, c = 3) a + b * c > f <- function(...) g(...) > > but formals (etc) is no longer very helpful. Is there an easy way to > programmatically create: > > f <- function(a=1, b=2, c=3) g(a=a, b=b, c=c) > > This comes up in ggplot2 where I alias many functions to hide the fact > that I'm using proto in the background, and I'd like the aliased > functions to be a little more user friendly in terms of revealing what > are valid arguments (and also to match up with the rdoc files which I > am building). > > Any ideas? > > Thanks, > > Hadley > > -- > http://had.co.nz/ > > __ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] Aliasing a function
I assume he wants to be able to change the formals although its confusing since the example uses the same formals in both cases. On Sat, Feb 23, 2008 at 6:32 PM, John Fox <[EMAIL PROTECTED]> wrote: > Dear Hadley, > > Why not just f <- g ? > > Regards, > John > > > John Fox, Professor > Department of Sociology > McMaster University > Hamilton, Ontario, Canada L8S 4M4 > 905-525-9140x23604 > http://socserv.mcmaster.ca/jfox > > > > > -Original Message- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > > project.org] On Behalf Of hadley wickham > > Sent: February-23-08 5:40 PM > > To: R-devel > > Subject: [Rd] Aliasing a function > > > > A simple way to alias a function is to do : > > > > g <- function(a = 1, b = 2, c = 3) a + b * c > > f <- function(...) g(...) > > > > but formals (etc) is no longer very helpful. Is there an easy way to > > programmatically create: > > > > f <- function(a=1, b=2, c=3) g(a=a, b=b, c=c) > > > > This comes up in ggplot2 where I alias many functions to hide the fact > > that I'm using proto in the background, and I'd like the aliased > > functions to be a little more user friendly in terms of revealing what > > are valid arguments (and also to match up with the rdoc files which I > > am building). > > > > Any ideas? > > > > Thanks, > > > > Hadley > > > > -- > > http://had.co.nz/ > > > > __ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > __ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] Aliasing a function
On Sat, Feb 23, 2008 at 5:52 PM, Gabor Grothendieck <[EMAIL PROTECTED]> wrote: > I assume he wants to be able to change the > formals although its confusing since the example > uses the same formals in both cases. Yes, that was an important point that I forgot to mention! Thanks for the pointer to formals but it doesn't work in this case: function (a = 1, b = 2, c = 3) g(...) > f(c=5) Error in f(c = 5) : '...' used in an incorrect context Hadley -- http://had.co.nz/ __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] Aliasing a function
Maybe something like this? (though it seems like it might be more
straightforward to do this sort of thing by text-processing a source
file then source'ing it in R).
> f <- function(a, b, c) c(a=a,b=b,c=c)
> attr(f, "source") <- NULL
> f
function (a, b, c)
c(a = a, b = b, c = c)
> g1 <- f
> ff <- formals(f)
> argtrans <- c(a="d", b="e", c="f")
> names(ff) <- argtrans
> g2 <- as.function(c(ff, as.call(c(list(as.name("f")),
lapply(argtrans, as.name)
> g2
function (d, e, f)
f(a = d, b = e, c = f)
> f(1,2,3)
a b c
1 2 3
> g1(a=1,b=2,c=3)
a b c
1 2 3
> g2(d=1,e=2,f=3)
a b c
1 2 3
>
-- Tony Plate
hadley wickham wrote:
> On Sat, Feb 23, 2008 at 5:52 PM, Gabor Grothendieck
> <[EMAIL PROTECTED]> wrote:
>
>> I assume he wants to be able to change the
>> formals although its confusing since the example
>> uses the same formals in both cases.
>>
>
> Yes, that was an important point that I forgot to mention! Thanks for
> the pointer to formals but it doesn't work in this case:
>
> function (a = 1, b = 2, c = 3)
> g(...)
>
>> f(c=5)
>>
> Error in f(c = 5) : '...' used in an incorrect context
>
> Hadley
>
>
>
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Re: [Rd] Aliasing a function
Thanks Tony (and others), for getting me started. I eventually ended up with:
TopLevel$build_accessor <- function(., extra_args = c()) {
layer <- if (.$class() %in% c("geom","stat", "position")) c(
list(mapping=NULL,data=NULL),
compact(list(
geom = if (exists("default_geom", .)) .$default_geom()$objname,
stat = if (exists("default_stat", .)) .$default_stat()$objname,
position = if (exists("default_pos", .)) .$default_pos()$objname
))
)
params <- .$params()
params <- params[names(params) != "..."]
args <- c(layer, params)
body <- ps(
.$myName(), "$", "new(",
if (length(args) > 0) ps(names(args),"=", names(args), collase =", "),
if (length(extra_args) > 0) ps(names(extra_args),"=", extra_args,
collase =", "),
"...",
")"
)
f <- function() {}
formals(f) <- as.pairlist(c(args, alist(... =)))
body(f) <- parse(text = body)
environment(f) <- globalenv()
f
}
-- obviously there are far more ggplot details in there than I had
first anticipated.
Hadley
On Mon, Feb 25, 2008 at 12:24 AM, Tony Plate <[EMAIL PROTECTED]> wrote:
> Maybe something like this? (though it seems like it might be more
> straightforward to do this sort of thing by text-processing a source
> file then source'ing it in R).
>
> > f <- function(a, b, c) c(a=a,b=b,c=c)
> > attr(f, "source") <- NULL
> > f
> function (a, b, c)
>
> c(a = a, b = b, c = c)
> > g1 <- f
> > ff <- formals(f)
> > argtrans <- c(a="d", b="e", c="f")
> > names(ff) <- argtrans
> > g2 <- as.function(c(ff, as.call(c(list(as.name("f")),
> lapply(argtrans, as.name)
> > g2
> function (d, e, f)
> f(a = d, b = e, c = f)
> > f(1,2,3)
> a b c
> 1 2 3
> > g1(a=1,b=2,c=3)
> a b c
> 1 2 3
> > g2(d=1,e=2,f=3)
> a b c
> 1 2 3
> >
>
> -- Tony Plate
>
>
>
>
> hadley wickham wrote:
> > On Sat, Feb 23, 2008 at 5:52 PM, Gabor Grothendieck
> > <[EMAIL PROTECTED]> wrote:
> >
> >> I assume he wants to be able to change the
> >> formals although its confusing since the example
> >> uses the same formals in both cases.
> >>
> >
> > Yes, that was an important point that I forgot to mention! Thanks for
> > the pointer to formals but it doesn't work in this case:
> >
> > function (a = 1, b = 2, c = 3)
> > g(...)
> >
> >> f(c=5)
> >>
> > Error in f(c = 5) : '...' used in an incorrect context
> >
> > Hadley
> >
> >
> >
>
>
--
http://had.co.nz/
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