[R] R and pointer
Prof Brian Ripley
ripley at stats.ox.ac.uk
Fri Aug 29 14:37:20 CEST 2003
On Fri, 29 Aug 2003, Laetitia Marisa wrote:
> I want to write a function that modify directly variables passed as
> parameters (the equivalent in C language of *ptr/&ptr) so that I don't
> have to return a list and to reaffect all my variables.
> Is it possible to do so in R?
Yes, with the .Call/.External interface (and there are examples in the ts
package). To a limited extent it is possible with .C(DUP=FALSE), but you
really don't want to go there.
I would want a very good understanding of R's copying semantics before
doing this (and those are liable to change, too).
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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