Points 1 and 2 are already fixed in R-devel, as I did indicate on R-help,
yesterday.
Point 3 is in the FAQ, no less:
* In R, if `x' is a list, then `x[i] <- NULL' and `x[[i]] <- NULL'
remove the specified elements from `x'. The first of these is
incompatible with S, where it is a no-op. (Note that you can set
elements to `NULL' using `x[i] <- list(NULL)'.)
Please don't mix up unrelated reports: point 3 has nothing to do with
matrix lists.
On Wed, 13 Mar 2002 rmh@surfer.sbm.temple.edu wrote:
### I got bit again by the same bugs I wrote about a year ago. ### The bugs are related to matrices and arrays of lists. ### 1. There is a clear inconsistency in how R handles two ### functionally equivalent statements. ### array() is able to take a list and create a matrix. ### matrix() is unable to create that matrix.
vector("list", 2)
[[1]] NULL [[2]] NULL
array(vector("list", 2), dim=c(2,1))
[,1] [1,] "NULL" [2,] "NULL"
tmpa <- array(vector("list", 2), dim=c(2,1))
class(tmpa)
NULL
is.array(tmpa)
[1] TRUE
is.matrix(tmpa)
[1] TRUE
tmpm <- matrix(vector("list", 2), nrow=2)
Error in matrix(vector("list", 2), nrow = 2) :
Unimplemented feature in copyVector
### 2. Here the matrix single-[ subscript is doing the wrong thing, ### without giving a warning.
tmp <- array(vector("list", 2), 1:2)
tmp
[,1] [,2] [1,] "NULL" "NULL"
tmp[1]
[[1]] NULL
tmp[[1]]
NULL
tmp[1,1]
[[1]] NULL
tmp[[1,1]]
NULL
list("abc")
[[1]] [1] "abc"
tmp[1] <- list("abc") ## assignment
tmp[1]
[[1]] [1] "abc"
tmp[[1]]
[1] "abc"
tmp[1,1] ## incorrect retrieval
[[1]] NULL
tmp[[1,1]]
[1] "abc"
tmp[1,2] <- list("def") ## refuse to do similar assignment
Error: incompatible types in subset assignment
### 3. subsetting a vector of lists doesn't behave the way I anticipate. ### It looks like NULL is not handled consistently inside a vector. ### Sometimes it can be an element, sometimes not.
tmpv <- vector("list", 2)
tmpv
[[1]] NULL [[2]] NULL
tmpv[1] <- "abcd" ## I assigned to the first element. tmpv ## Both elements are still here.
[[1]] [1] "abcd" [[2]] NULL
tmpv[1] <- NULL ## I assigned to the first element. tmpv ## The second element is gone.
[[1]] NULL
### This time the issue came up in an attempt to make abind work with R. ### abind() is a generalization of rbind and cbind to arrays. ### Tony Plate and I posted it to StatLib in 1996 ### (http://lib.stat.cmu.edu/S/abind). ### I would like you to consider adding abind to R. ### The posted abind doesn't work in R, for the reasons above and due to ### a difference in behavior of match.call between S -Plusand R that I am ### reporting in a separate bug report. ### There are two revised files, currently available at ### http://surfer.sbm.temple.edu/~rmh/abind.r ### http://surfer.sbm.temple.edu/~rmh/abind.test.in.r ### The documentation in statlib applies to these files. ### I will update the statlib version after I understand why R differs.
version
_ platform i386-pc-mingw32 arch x86 os Win32 system x86, Win32 status major 1 minor 4.1 year 2002 month 01 day 30 language R
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Brian D. Ripley, ripley@stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._