Duncan Murdoch wrote:
On 08/07/2008 5:01 PM, Rolf Turner wrote:
On 8/07/2008, at 7:38 PM, Fiona Johnson wrote:
Hi
I have just upgraded from R2.6.0 to R2.7.1 (running on Windows) and
a part
of my code that previously ran ok now gives an error. The following
is a
simple example to demonstrate my problem.
a <- array(c(1,2,3,4,5,6,rep(NA,6)),dim=c(6,2))
apply(a,2,sd,na.rm=T)
In R2.6.0 this gives (which is what I would like)
[1] 1.870829 NA
In R2.7.1 it gives the following error
"Error in var(x, na.rm = na.rm) : no complete element pairs"
As my columns are always either all NA or all numbers, I could get
around it
by replacing the NA's with 0's but if someone could shed some light
on why
the behaviour has changed in the new version or a better work
around it
would be much appreciated. I want to keep the columns of NA's because
ultimately I am plotting the results with contour and the NA's
refer to grid
cells not on land where I don't want to have contours.
I just scanned through the release announcements (from Peter
Dalgaard) about new
versions of R (R home page --> What's new? --> Archive of important
announcements)
and found nothing about new behaviour for sd/var/cov. So I cannot
contribute
to enlightenment about ``why''.
This is the relevant but not so obvious NEWS entry:
o co[rv](use = "complete.obs") now always gives an error if there
are no complete cases: they used to give NA if
method = "pearson" but an error for the other two methods. (Note
that this is pretty arbitrary, but zero-length vectors always
give an error so it is at least consistent.)
cor(use="pair") used to give diagonal 1 even if the variable
was completely missing for the rank methods but NA for the
Pearson method: it now gives NA in all cases.
(sd calls var, which calls cov internally.)
Thanks. I was searching for it as well... (BTW, Rolf, I'm not the
oracle, I just copy parts of the NEWS file into release announcements.
The file itself is readily available, as others point out.)
I think this has come up before but I forgot the details.
It _is_ a bit odd that the variance of an empty vector is an error but
that of a one-element vector is NA, and the difference var(NA,na.rm=T)
and var(numeric(0)) is not too clear either.
Also,
> var(NA,use="pair")
[1] NA
> var(NA,use="co")
Error in var(NA, use = "co") : no complete element pairs
--
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
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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