[R] methods on missing data

[Prof Brian Ripley]

On Wed, 6 Jun 2001 Maciej.Hoffman-Wecker at evotecoai.com wrote:

> I have 2 >issues< concerning methods applied to missing data.
> I think they're bugs, but who knows.
>
> 1. var(NA) returns
>
>      Error in var(NA) : missing observations in cov/cor

It works exactly as documented: see ?var.  Did you intend
to use

> var(NA, na.rm=T)
[1] NA

?  I suspect so, so the bug does not seem to be in R....

> instead of NA. I expanded the summary-function to my.summary
> including SDev, in order to use it with tapply, which crashes
> in case of groups with no valid data.
>
> 2. is a similar problem. I use tapply with hist. On groups
> without valid data it crashes, like hist(as.numeric(c(NA)))
> returning
>
>      Error in pretty(rx, n = nnb, min.n = 1) : x must be numeric
>
> hist(as.numeric(c(NA)),breaks=c(1,2)) works, as it does not use "pretty".
>
> I know these are very special cases, but unfortunately they kill the whole
> process.
>
> I can figure out some personal solution, but I hope for a professional one.
>
> Hope this is kind of helpful.
>
> Maciej
>
>
>
> sysname "Linux"
> release "2.4.4"
> version "#1 SMP Wed May 2 20:47:43 CEST 2001"
> nodename "lxnf"
> machine "i686"
> login "unknown"
> user "hoffman"
>
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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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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