> I don't see how that solves
> the example I gave of extracting "plot(x=0, y=1)" from tstFn <-
> function()plot(0, 1).
Try
> match.call(definition=plot, call=body(tstFn))
plot(x = 0, y = 1)
plot() is not a great example, since some of its methods do not have an
argument called 'y' (e.g., plot.stepfun) and it has a lot of ... arguments which
you need to go to the help file for.
Bill Dunlap
TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: Spencer Graves [mailto:spencer.gra...@structuremonitoring.com]
> Sent: Tuesday, April 08, 2014 4:53 PM
> To: William Dunlap; R list
> Subject: Re: [R] getting arg names in function calls?
>
> Hi, Bill:
>
>
> Thanks for the reply. Unfortunately, I don't see how that solves
> the example I gave of extracting "plot(x=0, y=1)" from tstFn <-
> function()plot(0, 1).
>
>
> As I noted, body(tstFn) returns "plot(0, 1)" as an "language"
> object of class "call". My challenge is to convert that into something
> similar, with explicit names for the arguments.
>
>
> Any thoughts?
> Spencer
>
>
> On 4/7/2014 3:18 PM, William Dunlap wrote:
> > Look at match.call(). E.g.,
> > > f <- function(x, y = log2(x), ...) match.call()
> > > f()
> > f()
> > > f(1, x=2, anotherArg=3, 4)
> > f(x = 2, y = 1, anotherArg = 3, 4)
> > or, using its 'definition' and 'call' arguments directly
> > > match.call(function(x, y, ...)NULL, quote(foo(1, x=2, extraArg=3, 4)))
> > foo(x = 2, y = 1, extraArg = 3, 4)
> > > match.call(function(x, y, ...)NULL, quote(foo(1, x=2, extraArg=3, 4)),
> expand.dots=FALSE)
> > foo(x = 2, y = 1, ... = list(extraArg = 3, 4))
> >
> > Bill Dunlap
> > TIBCO Software
> > wdunlap tibco.com
> >
> >
> >> -----Original Message-----
> >> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf
> >> Of Spencer Graves
> >> Sent: Monday, April 07, 2014 3:05 PM
> >> To: R list
> >> Subject: [R] getting arg names in function calls?
> >>
> >> How can I convert "plot(0, 1)" into "plot(x=0, y=1)"?
> >>
> >>
> >> More generally, how can I get argument names assigned to function
> >> calls in "language" objects?
> >>
> >>
> >> Example:
> >>
> >>
> >> tstFn <- function()plot(0, 1)
> >> bo <- body(tstFn)
> >>
> >>
> >> tstFnxy <- function()plot(x=0, y=1)
> >> boxy <- body(tstFnxy)
> >>
> >>
> >> Is there a function that will modify "bo" to match "boxy"?
> >>
> >>
> >> My current solution requires me to know the names of the
> >> arguments for "plot" (in this example). I'd prefer a more general
> >> solution.
> >>
> >>
> >> Thanks,
> >> Spencer
> >>
> >>
> >> p.s. I'm trying to create an animation by repeatedly calling a function
> >> that contains something like text(0, 1, "abc"). By computing on the
> >> language object 'text(0, 1, "abc")', I can call text(0, 1, 'a') the
> >> first time, text(0, 1, 'ab') the second, and text(0, 1, 'abc') the
> >> third. The function will be more general if I can get the names of the
> >> arguments as just described.
> >>
> >> ______________________________________________
> >> R-help@r-project.org mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-help
> >> PLEASE do read the posting guide
> >> http://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
>
>
> --
> Spencer Graves, PE, PhD
> President and Chief Technology Officer
> Structure Inspection and Monitoring, Inc.
> 751 Emerson Ct.
> San José, CA 95126
> ph: 408-655-4567
> web: www.structuremonitoring.com
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