[R] Automatical download of needed packages from CRAN

[Prof Brian Ripley]

On Fri, 29 Sep 2006, Søren Højsgaard wrote:

> I write a package foo which requires a package bar (from CRAN) to work. 
> So in the DESCRIPTION file I write Depends: bar. I would like it to be 
> so that when one installs foo, then it is automatically checked whether 
> bar is installed, and if not then bar is also installed at the same 
> time. I remember having seen packages which do so, but I can not figure 
> out the mechanism 'Depends: bar' in the DESCRIPTION file does not solve 
> the problem. Can anyone help?

It does if you use install.packages(dependencies=TRUE), the default from 
the Windows GUI menu.

> A related question: How to check programmatically that a specific 
> package is loaded?

Via search(): there are lots of examples in the R help files.  ?termplot 
is one.

>
> Best regards
> Søren
>
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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)
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