S4 generics can specify a valueClass. Perhaps that could be used in those cases.
On Wed, Nov 4, 2009 at 3:24 PM, Duncan Murdoch <murd...@stats.uwo.ca> wrote: > On 11/4/2009 12:15 PM, William Dunlap wrote: >>> >>> -----Original Message----- >>> From: r-devel-boun...@r-project.org >>> [mailto:r-devel-boun...@r-project.org] On Behalf Of Duncan Murdoch >>> Sent: Wednesday, November 04, 2009 8:47 AM >>> To: michael.m.spie...@gmail.com >>> Cc: r-b...@r-project.org; r-de...@stat.math.ethz.ch >>> Subject: Re: [Rd] error in install.packages() (PR#14042) >>> >>> On 11/4/2009 11:05 AM, michael.m.spie...@gmail.com wrote: >>> > Full_Name: Michael Spiegel >>> > Version: 2.10 >>> > OS: Windows Vista >>> > Submission from: (NULL) (76.104.24.156) >>> > > > The following error is produced when attempting to call >>> > > > install.packages. Here >>> > is the results of the traceback: >>> > >> source('http://openmx.psyc.virginia.edu/getOpenMx.R') >>> > Error in f(res) : invalid subscript type 'list' >>> >> traceback() >>> > 7: f(res) >>> > 6: available.packages(contriburl = contriburl, method = method) >>> > 5: .install.winbinary(pkgs = pkgs, lib = lib, contriburl = contriburl, >>> > > method = method, available = available, destdir = destdir, > >>> > dependencies = dependencies, ...) >>> > 4: install.packages(pkgs = c("OpenMx"), repos = repos) >>> > 3: eval.with.vis(expr, envir, enclos) >>> > 2: eval.with.vis(ei, envir) >>> > 1: source("http://openmx.psyc.virginia.edu/getOpenMx.R";) >>> > > I've tracked the error down to somewhere in available.packages >>> > > defined in >>> > src\library\utils\R\packages.R. I am guessing that the error in >>> > version 2.10 >>> > has something to do with the change: "available.packages() gains a >>> > 'filters' >>> > argument for specifying the filtering operations performed on the >>> > packages found >>> > in the repositories." >>> >>> I've found the error, and will fix and commit to R-devel and R-patched. >>> >>> For future reference: the problem was that it assigned the result of >>> sapply() to a subset of a vector. Normally sapply() simplifies its result >>> to a vector, but in this case the result was empty, so sapply() returned an >>> empty list; assigning a list to a vector coerced the vector to a list, and >>> then the "invalid subscript type 'list'" came soon after. >> >> I've run into this sort of problem a lot (0-long input to sapply >> causes it to return list()). A related problem is that when sapply's >> FUN doesn't always return the type of value you expect for some >> corner case then sapply won't do the expected simplication. If >> sapply had an argument that gave the expected form of FUN's output >> then sapply could (a) die if some call to FUN didn't return something >> of that form and (b) return a 0-long object of the correct form >> if sapply's X has length zero so FUN is never called. E.g., >> sapply(2:0, function(i)(11:20)[i], FUN.VALUE=integer(1)) # die on >> third iteration >> sapply(integer(0), function(i)i>0, FUN.VALUE=logical(1)) # return >> logical(0) >> >> Another benefit of sapply knowing the type of FUN's return value is >> that it wouldn't have to waste space creating a list of FUN's return >> values but could stuff them directly into the final output structure. >> A list of n scalar doubles is 4.5 times bigger than double(n) and the >> factor is 9.0 for integers and logicals. > > > What do you think of the behaviour of the sapply function below? (I > wouldn't put it into R as it is, I'd translate it to C code to avoid the > lapply call; but I'd like to get the behaviour right before doing that.) > > This one checks that the length() and typeof() results are consistent. If > the FUN.VALUE has names, those are used (but it doesn't require the names > from FUN to match). > > Duncan Murdoch > > sapply <- function(X, FUN, ..., simplify = TRUE, USE.NAMES = TRUE, > FUN.VALUE) > { > FUN <- match.fun(FUN) > answer <- lapply(X, FUN, ...) > if(USE.NAMES && is.character(X) && is.null(names(answer))) > names(answer) <- X > if(simplify) { > if (missing(FUN.VALUE)) { > if ((!length(answer)) > || length(common.len <- unique(unlist(lapply(answer, > length)))) != 1L) > return(answer) > common.names <- names(answer[[1L]]) > } else { > common.len <- length(FUN.VALUE) > common.type <- typeof(FUN.VALUE) > common.names <- names(FUN.VALUE) > if (length(answer)) { > if (any( unlist(lapply(answer, length)) != common.len )) > stop(sprintf("%s values must be of length %d", "FUN", > common.len)) > if (any( unlist(lapply(answer, typeof)) != common.type )) > stop(sprintf("%s values must be of type '%s'", "FUN", > common.type)) > if (is.null(common.names)) > common.names <- names(answer[[1L]]) > } else if (length(FUN.VALUE) > 1) > return(array(FUN.VALUE[0], dim=c(common.len, 0), > dimnames= if(!is.null(common.names)) > list(common.names,character(0)))) > else > return(FUN.VALUE[0]) > } > if(common.len == 1L) > unlist(answer, recursive = FALSE) > else if(common.len > 1L) > array(unlist(answer, recursive = FALSE), > dim= c(common.len, length(X)), > dimnames= if(!(is.null(common.names) & > is.null(n2 <- names(answer)))) > list(common.names,n2)) > else answer > } else answer > } > > ______________________________________________ > 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
