[R-SIG-Mac] NA handling in 2.7.0 versus 2.6.2 for SD
Prof Brian Ripley
ripley at stats.ox.ac.uk
Tue Apr 22 19:03:56 CEST 2008
On Tue, 22 Apr 2008, William Revelle wrote:
> Hi,
> When comparing how R2.7.0 handles missing values I discovered that
> it differs from 2.6.2 (at least for the sd function). In
> particular, if a column of a matrix is all NA, sd in 2.7.0 throws an
> error while in 2.6.2 it just returns NA for that column. Is this
> intentional?
I presume you mean sd(na.rm=TRUE): the default behaviour is unchanged.
This is intentional and documented in the NEWS file as a BUG FIX.
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.)
sd() calls var = cov. Why would anyone expect
> sd(numeric(0))
Error in var(x, na.rm = na.rm) : 'x' is empty
> sd(NA_real_, na.rm=TRUE)
[1] NA
> sd(na.omit(NA_real_))
Error in var(as.vector(x), na.rm = na.rm) : 'x' is empty
(from 2.6.2)?
>
>> x <- matrix(1:50,ncol=5)
>> sd(x)
> [1] 3.027650 3.027650 3.027650 3.027650 3.027650
>> x[,1] <- NA
>> sd(x,na.rm=TRUE)
> Error in var(x, na.rm = na.rm) : no complete element pairs
>
>
>
> R version 2.7.0 RC (2008-04-21 r45421)
> i386-apple-darwin8.10.1
>
> locale:
> en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>
>
> compare this to version 2.6.2
>> x <- matrix(1:50,ncol=5)
>> sd(x)
> [1] 3.027650 3.027650 3.027650 3.027650 3.027650
>
>> x[,1] <- NA
>> sd(x,na.rm=TRUE)
> [1] NA 3.027650 3.027650 3.027650 3.027650
>
>> sessionInfo()
> R version 2.6.2 (2008-02-08)
> i386-apple-darwin8.10.1
>
> locale:
> en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>>
>
> Thanks for all the great work. Sorry not to have detected this sooner.
>
> Bill
>
>
> --
> William Revelle http://personality-project.org/revelle.html
> Professor http://personality-project.org/personality.html
> Department of Psychology http://www.wcas.northwestern.edu/psych/
> Northwestern University http://www.northwestern.edu/
> Use R for statistics: http://personality-project.org/r
>
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--
Brian D. Ripley, ripley at 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 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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