[Rd] (PR#8192) [ subscripting sometimes loses names
p.dalgaard at biostat.ku.dk
Sat Jan 31 16:13:30 CET 2009
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
>>>> 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":
> 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
> BAD $vec.1[] $vec.1[]
> a c <NA> a c no
> 1 3 NA 1 3 NA
> I just tracked this one down, and can put together this simple example:
> > (1:3)["no"]
>  NA
> where I think you would want the name "no" attached to the output. (Or
> maybe your more complicated example is wanted? You don't explain.) But
> that looks like documented behaviour to me: according to my reading of
> "Indexing by vectors" in the R Language Definition manual, it should
> give the same answer as (1:3), and it does. So it's not a bug, but a
> wishlist item.
> And the other two cases where you list "BAD" behaviour? I didn't track
> them down.
I did, and they boil down to variations of
 1 2 3
but it's not obvious that the result should be named using the row.names
and (in particular) whether or why it should differ from .....[] and
....$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 Øster 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
More information about the R-devel