(PR#8192) [ subscripting sometimes loses names
Duncan Murdoch wrote:
On 31/01/2009 7:31 AM, Andrew Piskorski wrote:
This (tangential) discussion really should be a separate thread so I changed the subject line above. On Fri, Jan 30, 2009 at 11:51:00AM -0500, Simon Urbanek wrote:
Subject: Re: [Rd] (PR#13487) Segfault when mistakenly calling [.data.frame
My boss was debugging an issue in our R code. We have our own "[...." functions, because stock R drops names when subscripting.
... if you tell it to do so, yes. If you tell it to not do that, it won't ... ever tried drop=FALSE ?
Simon, no, the drop=FALSE argument has nothing to do with what Christian was talking about. The kind of thing he meant is PR# 8192, "Subject: [ subscripting sometimes loses names": http://bugs.r-project.org/cgi-bin/R/wishlist?id=8192
In that bug report you were asked to provide simple examples, and you
didn't. I imagine that's why there was no action on it. It is not that
easy for someone else to actually find the simple example that led you
to print
$vec.1
BAD $vec.1[[1]] $vec.1[[2]]
a c <NA> a c no
1 3 NA 1 3 NA
I just tracked this one down, and can put together this simple example:
> (1:3)["no"]
[1] NA where I think you would want the name "no" attached to the output. (Or maybe your more complicated example is wanted? You don't explain.) But that looks like documented behaviour to me: according to my reading of "Indexing by vectors" in the R Language Definition manual, it should give the same answer as (1:3)[4], and it does. So it's not a bug, but a wishlist item. And the other two cases where you list "BAD" behaviour? I didn't track them down.
I did, and they boil down to variations of > data.frame(val=1:3,row.names=letters[1:3])[,1] [1] 1 2 3 but it's not obvious that the result should be named using the row.names and (in particular) whether or why it should differ from .....[[1]] and ....$val. Given that for most purposes, extracting the relevant names would just be unnecessary red tape, I'd say that we can do without it.
O__ ---- Peter Dalgaard ?ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907