[R] Trying to learn how to write an "advanced" function
Greg Snow
538280 @end|ng |rom gm@||@com
Thu Mar 16 16:28:14 CET 2023
I think the tricky part here is the different types of `quote`. I
would use `bquote` here, try:
doit <- function(x){
ds <- deparse(substitute(x))
cat("1\n")
print(ds)
eval(bquote(lm(.(ds))),parent.frame())
}
Just note that getting the parent.frame() portion right in anything
more complicated can be very tricky, it is better to pass in the data.
On Thu, Mar 16, 2023 at 8:54 AM Sorkin, John <jsorkin using som.umaryland.edu> wrote:
>
> Although I owe thanks to Ramus and Ivan, I still do not know how to write and "advanced" function.
>
> My most recent try (after looking at the material Ramus and Ivan set) still does not work. I am trying to run the lm function on two different formulae:
> 1) y~x,
> 2) y~x+z
> Any corrections would be appreciated!
>
> Thank you,
> John
>
>
> doit <- function(x){
> ds <- deparse(substitute(x))
> cat("1\n")
> print(ds)
> eval(lm(quote(ds)),parent.frame())
> }
>
> # define data that will be used in regression
> y <- 1:10
> x <- y+rnorm(10)
> z <- c(rep(1,5),rep(2,5))
> # Show what x, y and z look like
> rbind(x,y,z)
>
> # run formula y~x
> JD <- doit(y~x)
> JD
>
> # run formula y~x+z
> JD2 <- doit(y~x+z)
> JD2
>
>
>
> ________________________________________
> From: R-help <r-help-bounces using r-project.org> on behalf of Rasmus Liland <jral using posteo.no>
> Sent: Thursday, March 16, 2023 8:42 AM
> To: r-help
> Subject: Re: [R] Trying to learn how to write an "advanced" function
>
> On 2023-03-16 12:11 +0000, Sorkin, John wrote:
> > (1) can someone point me to an
> > explanation of match.call or match
> > that can be understood by the
> > uninitiated?
>
> Dear John,
>
> the man page ?match tells us that match
> matches the first vector against the
> second, and returns a vector of indecies
> the same length as the first, e.g.
>
> > match(c("formula", "data", "subset", "weights", "na.action", "offset"), c("Maryland", "formula", "data", "subset", "weights", "na.action", "offset", "Sorkin", "subset"), 0L)
> [1] 2 3 4 5 6 7
>
> perhaps a bad answer ...
>
> > (2) can someone point me to a document
> > that will help me learn how to write
> > an "advanced" function?
>
> Perhaps the background here is looking
> at the lm function as a basis for
> writing something more advanced, then
> the exercise becomes looking at
> dput(lm), understanding every line by
> looking up all the functions you do not
> understand in the man pages e.g. ?match.
> Remember, you can search for things
> inside R by using double questionmark,
> ??match, finding versions of match
> existing inside other installed
> packages, e.g. raster::match and
> posterior::match, perhaps this exercise
> becomes writing ones own version of lm
> inside ones own package?
>
> Best,
> Rasmus
>
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> and provide commented, minimal, self-contained, reproducible code.
--
Gregory (Greg) L. Snow Ph.D.
538280 using gmail.com
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