similar to: question on docs for delayedAssign and substitute

Hello, ?delayedAssign presents substitute() as a way to look at the expression in the promise. However, msg <- "old" delayedAssign("x", msg) msg <- "new!" x #- new! substitute(x) #- x (was 'msg' ?) Here, we just got 'x'... shouldn't we got 'msg'? Same result when the promise is not evaluated yet: delayedAssign("x",

Duncan, Thank you for the clarification on how delayedAssign works. Should R-level interfaces to promise objects ever become available, I expect they would at time come in handy. On the subject of substitute and delayedAssign, I do have a follow-up question for the list. I'm trying to convert a named list of expression objects into an environment of promise objects. After conversion, each

A user question today has me stumped. Can you advise me, please? User wants a matrix that has some numbers, some variables, possibly even some function names. So that has to be a character matrix. Consider: > BM <- matrix("0.1", 5, 5) Use data.entry(BM) or similar to set some to more abstract values. > BM[3,1] <- "a" > BM[4,2] <- "b" >

I'm not sure if this is a known peculiarity or a bug, but I stumbled across what I think is very odd behavior from delayedAssign. In the below example x switches values the first two times it is evaluated. > delayedAssign("x", {x <- 2; x+3}) > x==x [1] FALSE > delayedAssign("x", {x <- 2; x+3}) > x [1] 5 > x [1] 2 The ?delayedAssign documentation says

I noticed something recently that I thought was odd: delayedAssign("x", { Sys.sleep(5); 1 }) x ## Hit Ctrl-C within the first second or 2 gives me: > delayedAssign("x", { Sys.sleep(5); 1 }) > x ## Hit Ctrl-C within the first second or two > x Error: recursive default argument reference > My only problem here is that now I'm stuck---there's no way

Hi all, The help for delayedAssign suggests that you can use substitute to access the expression associated with a promise, and the help for substitute says: "If it is a promise object, i.e., a formal argument to a function or explicitly created using ?delayedAssign()?, the expression slot of the promise replaces the symbol. But this doesn't seem to work: > a <- 1 > b <- 2

The last two lines of example(delayedAssign) give this: > e <- (function(x, y = 1, z) environment())(1+2, "y", {cat(" HO! "); pi+2}) > (le <- as.list(e)) # evaluates the promises $x <promise: 0x032b31f8> $y <promise: 0x032b3230> $z <promise: 0x032b3268> which contrary to the comment appears unevaluated. Is the comment wrong or is it supposed to

Certain errors seem to generate messages that are less informative than most -- they just tell you which function an error happened in, but don't indicate which line or expression the error occurred in. Here's a toy example: > f <- function(x) {a <- 1; y <- x[list(1:3)]; b <- 2; return(y)} > options(error=NULL) > f(1:3) Error in f(1:3) : invalid subscript type

I downloaded: http://www.bioconductor.org/data/metaData/hgu95av2_1.7.0.tar.gz described as: Package: hgu95av2 Title: A data package containing annotation data for hgu95av2 Version: 1.7.0 Created: Wed Jan 12 16:57:23 2005 Author: Lin,Chenwei Description: Annotation data file for hgu95av2 assembled using data from public data repositories Maintainer:

I was trying to create a function with a value computed at creation time, using substitute(), but I got results I don't understand: > this.is.R Error: Object "this.is.R" not found > substitute(this.is.R <- function() X, list(X=!is.null(options("CRAN")[[1]]))) this.is.R <- function() TRUE > # the above expression as printed is what I want for the

Running under Windows XP 64 bit, as.POSIXlt()/as.POSIXct() seem to think that US time zones (EST5EDT, MST7MDT) switched from daylight savings back to standard time on Oct 28, 2007, whereas the switch is actually on Sun Nov 04, 2007. Examples: > Sys.timezone() [1] "Mountain Daylight Time" > as.POSIXct("2007-10-30 12:38:47") [1] "2007-10-30 12:38:47 Mountain

I find that Sys.glob() doesn't like UNC paths where the initial slashes are backslashes. The help page for Sys.glob() doesn't specificly mention UNC paths, but does say: "File paths in Windows are interpreted with separator \ or /." Is the failure to treat a path beginning with a double-backslash as a UNC network drive path the intended behavior? E.g., on a Windows system

There looks to be a bug in do_attr() (src/main/attrib.c): incorrect partial matches of attribute names can be returned when there are an odd number of partial matches. E.g.: > x <- c(a=1,b=2) > attr(x, "abcdef") <- 99 > attr(x, "ab") [1] 99 > attr(x, "abc") <- 100 > attr(x, "ab") # correctly returns NULL because of ambig

library() seems to remember the location of a package when I give it a lib.loc, and then use that version thereafter, even if I don't supply lib.loc again. Is there any way I can load different versions of a package in one R session? -- I don't seem to able to simply detach the package and then load a different version from a different library location. $ R [...startup info...] >

R-devel, I used the 'substitute' function to create labels for objects inside an environment, without actually evaluating the objects, as the objects might be promises. However, I was surprised to see that 'substitute' returns the expression slot of the original promise even after the promise has been forcibly evaluated. (Doesn't the promise go away after evaluation?) This

Consider the following example: # substitute a with b in the indicated function. Seems to work. > z <- substitute( function()a+1, list(a=quote(b)) ) > z function() b + 1 # z is an object of class call so use eval # to turn it into an object of class expression; however, # when z is evaluated, the variable a returns. > eval(z) function()a+1 Why did a suddenly reappear again

Hi, All: Is there a way to identify whether any users are using a particular package in a shared network R installation? I ask, because we have such a multiple-user installation and when I tried to install a package using Rgui that was in use by Rterm on a single-user installation, 'install.packages' deleted the existing package but failed to install the new version;

Hi, in help("R_GSCMD") it says "R_GSCMD: Optional. The path to Ghostscript, used by dev2bitmap, bitmap and embedFonts. Consulted when those functions are invoked.". However, if 'R_GSCMD' contains a full pathname to the Ghostscript executable (as above "path" indicates), e.g. > Sys.getenv("R_GSCMD") [1] "C:\\Program

Hi all, The documentation for substitute currently reads: Substitution takes place by examining each component of the parse tree as follows: If it is not a bound symbol in ?env?, it is unchanged. If it is a promise object, i.e., a formal argument to a function or explicitly created using ?delayedAssign()?, the expression slot of the promise replaces the symbol. If it is an ordinary variable,

On Mon, Jan 26, 2015 at 12:24 PM, Hadley Wickham <h.wickham at gmail.com> wrote: > If it was any other environment than the global, you could use substitute: > > e <- new.env() > delayedAssign("foo", stop("Hey!"), assign.env = e) > substitute(foo, e) > > delayedAssign("foo", stop("Hey!")) > substitute(foo) Hmm... interesting