similar to: understanding as.list(substitute(...()))

I probably need to be more specific. What confuses me is not the use of substitute, but the parenthesis after the dots. It clearly works and I can make guesses as to why but it is definitely not obvious. The following function gives the same final result but I can understand what is happening. dots <- function (...) { exprs <- substitute(list(...)) as.list(exprs[-1]) } In the

You need to understand what substitute() does -- see ?substitute and/or a tutorial on "R computing on the language" or similar. Here is a simple example that may clarify: > dots <- function(...) as.list(substitute(...())) > dots(log(foo)) [[1]] log(foo) ## a call, a language object > dots2 <- function(...) as.list(...) > dots2(log(foo)) Error in as.list(...) :

Hi Tim, I have also asked a similar question a couple of months ago, and someone else did the same recently, maybe on r-devel. We received no "official" response, but Deepayan Sarkar (R Core Team member) claimed that: " There is no documented reason for this to work (AFAIK), so again, I would guess this is a side-effect of the implementation, and not a API feature you should

Interestingly, as.list(substitute(...())) also works. On Sun, Aug 12, 2018 at 1:16 PM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote: > On 12/08/2018 4:00 PM, Henrik Bengtsson wrote: >> >> Hi. For any number of *known* arguments, we can do: >> >> one <- function(a) list(a = substitute(a)) >> two <- function(a, b) list(a = substitute(a), b =

Since you're already using bang-bang ;) library(rlang) dots1 <- function(...) as.list(substitute(list(...)))[-1L] dots2 <- function(...) as.list(substitute(...())) dots3 <- function(...) match.call(expand.dots = FALSE)[["..."]] dots4 <- function(...) exprs(...) bench::mark( dots1(1+2, "a", rnorm(3), stop("bang!")), dots2(1+2, "a",

I've just updated to R 4.0.2 but am unsure how to get packages from the COPR repository to update to those built under the new version of R. FI - I'm not currently using CoprManager just trying to update/install from terminal. Regards Tim [[alternative HTML version deleted]]

Hi. For any number of *known* arguments, we can do: one <- function(a) list(a = substitute(a)) two <- function(a, b) list(a = substitute(a), b = substitute(b)) and so on. But how do I achieve the same when I have: dots <- function(...) list(???) I want to implement this such that I can do: > exprs <- dots(1+2) > str(exprs) List of 1 $ : language 1 + 2 as well as: >

Thanks all, this was very helpful. Peter's finding - dots2() below - is indeed interesting - I'd be curious to learn what goes on there. The different alternatives perform approximately the same; dots1 <- function(...) as.list(substitute(list(...)))[-1L] dots2 <- function(...) as.list(substitute(...())) dots3 <- function(...) match.call(expand.dots = FALSE)[["..."]]

The news feeds (e.g. https://developer.r-project.org/blosxom.cgi/R-devel/NEWS) have some stray "\abbr" floating around. Do they need generating with a more recent version of R-devel? I've run tools::Rd2txt on https://svn.r-project.org/R/trunk/doc/NEWS.Rd and r85550 does seem to remove these abberations (compared to the same function calling on an unpatched 4.3.2 where they

Hi all, In the package rtlu, I use the function savePlot. It is convenient since it let the user decide in which graphic format he wants his graph to be export. But when I run R CMD check, I get the following message : > rtlu(V1,fileOutput="First.tex",textBefore="\\section{Variable 1 to 3}",graphName="V1") Error in savePlot(filename = nomBarplot, type = type)

Hi, Down a cascade of function calls, I want to use the curve function with an expression that is a variable. For various reason, this variable must be a character object and cannot be an expression as required by the curve function. How do I convert my variable into a expression that is accepted by curve? Thanks in advance for your help. ## The following attempts do not work myf <-

Sebastian: This is somewhat arcane, perhaps even a bug (correction on this welcomed). The problem is that the "expr" argument to curve() must be an actual expression, not a call to parse that evaluates to an expression. If you look at the code of curve() you'll see why (substitute() does not evaluate expr in the code). Another simple workaround other than sticking in the eval()

On 21/02/18 11:36, Spencer Graves wrote: > Hi, All: > > > ????? How can I get the names of all the arguments in dots(...)? > > > ????? I'm able to get the name of the first argument but not the second: > > > > deparseDots <- function(...){ > ? deparse(substitute(...)) > } > a <- 1 > b <- 2 > deparseDots(a, b) > [1]

Typo: should be NULL not NUL of course An alternative approach closer to your original attempt is to use do.call() to explicitly evaluate the expr argument: w <- "1 + x^2" do.call(curve, list(expr = parse(text = w), ylab ="y")) Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus

Hi, All: ????? How can I get the names of all the arguments in dots(...)? ????? I'm able to get the name of the first argument but not the second: deparseDots <- function(...){ ? deparse(substitute(...)) } a <- 1 b <- 2 deparseDots(a, b) [1] "a" ????? I'd like to get c('a', 'b'). ????? Thanks, ????? Spencer Graves > sessionInfo() R

A private reply by Martin made me realize that I was wrong about stopifnot(exprs=TRUE) . It actually works fine. I apologize. What I tried and was failed was stopifnot(exprs=T) . Error in exprs[[1]] : object of type 'symbol' is not subsettable The shortcut assert <- function(exprs) stopifnot(exprs = exprs) mentioned in "Warning" section of the documentation similarly fails

Another possible shortcut definition: assert <- function(exprs) do.call("stopifnot", list(exprs = substitute(exprs), local = parent.frame())) After thinking again, I propose to use ??? ? ? stop(simpleError(msg, call = if(p <- sys.parent()) sys.call(p))) - It seems that the call is the call of the frame where stopifnot(...) is evaluated. Because that is the correct context, I

Hi all I am having troubles making sense of why code (1) below fails but code (2) below works. Code (1): > phi.1 <- 1 > plot(0 ~ 0, + main=substitute(paste("A vaue for ",phi," = ",phival), list(phival=phi.1)) ) Error in paste("The two deviances for ", phi, " = ", 2) : Object "phi" not found But this works: Code (2): >

Dear R Core Team, I learnt approx. two years ago in this mailing list that one can use the following "trick" to get a (dotted pair)list of the ellipsis arguments inside a function: `substitute(...())` Now my problem is that I can not find any occurrence of this call within the R source - the most frequent solution there is `substitute(list(...))[-1L] ` I would like to know if: 1)

Hi, is there an elegant way to use 'substitute' with '...' arguments? My first try was this: > f1 <- function(...) substitute(...) > f1( 2+7, "foo", 3+5 ) 2 + 7 As you can see, substitute acts only on the first argument. So I tried > f2 <- function(...) substitute(list(...)) > f2( 2+7, "foo", 3+5 ) list(2 + 7, "foo", 3 + 5)