[R] Install package automatically if not there?

[Prof Brian Ripley]

On Thu, 24 Jun 2010, Bert Gunter wrote:

> You mean if a "package" has been installed?! (big difference)
>
> ?installed.packages  or ?.packages with all.available = TRUE

Various people have suggested those.  Can I point out that they are 
very slow with a few thousand packages installed, especially on 
Windows file systems and particularly the first. (A prime example of 
how not to do it is 'ff', which calls installed.packages() to find its 
own version: that takes minutes to load on my Windows desktop.)

You can use library(logical.return=TRUE) (or its wrapper require()) or 
do as that does and use .find.package() (or its wrapper 
system.file()).

> ?install.packages
>
>
>
> Bert Gunter
> Genentech Nonclinical Biostatistics
>
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
> Behalf Of Ralf B
> Sent: Thursday, June 24, 2010 12:26 PM
> To: r-help at r-project.org
> Subject: [R] Install package automatically if not there?
>
> Hi fans,
>
> is it possible for a script to check if a library has been installed?
> I want to automatically install it if it is missing to avoid scripts
> to crash when running on a new machine...
>
> Ralf
>
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>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
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