[R] Bug in sd() and var() in handling vectors of NA (R version 2.7.1)?

[Prof Brian Ripley]

There was a bug in 2.6.1 which has since been corrected: there is no need 
to report corrected bugs in obsolete versions.  Two different ways to 
compute the sd of a zero-length vector gave different answers.

This is covered by the following NEWS item for 2.7.0 (version from 
R-patched)

     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.)

         Since sd(na.rm=TRUE) and var(na.rm=TRUE) both call cov(use =
         "complete.obs"), this applies also to them.


On Tue, 29 Jul 2008, Marisa Laetitia wrote:

> In the previous versions of R (2.6.1), when a vector of NA was given to the functions 'sd' or 'var' with parameter na.rm = TRUE, it used to return NA. Now (2.7.1) it returns an ERROR :
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> Example in 2.6.1:
>
>> sd(c(NA, NA, NA, NA), na.rm = TRUE)
>
> [1] NA
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> Example in 2.7.1:
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>> sd(c(NA, NA, NA, NA), na.rm = TRUE)
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> Error in var(x, na.rm = na.rm) : paires d'?l?ments incompl?tes
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> We are actually wondering if it is a bug to report, or if we have to manage it in our own R scripts.
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> Thanks a lot, best regards,
>
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> Laetitia
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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