# [Rd] R/S indexing difference

**ripley@stats.ox.ac.uk
**
ripley@stats.ox.ac.uk

*Fri Feb 7 22:19:02 2003*

The S version is at least documented (p.157 of the Green book). I can't
find any documentation of the R version, not even in the so-called
`R Language Definition': is there one?
On 6 Feb 2003, Peter Dalgaard BSA wrote:
>* ripley@stats.ox.ac.uk writes:
*>*
*>* > Is this intentional?
*>* >
*>* > R:
*>* > > x <- 1:7
*>* > > x[c(1, NA, 3)] <- -(4:6)
*>* > > x
*>* > [1] -4 2 -6 4 5 6 7
*>* >
*>* > so NAs are treated as FALSE
*>* >
*>* > S+6.1:
*>* > > x <- 1:7
*>* > > x[c(1, NA, 3)] <- -(4:6)
*>* > Warning messages:
*>* > Replacement length not a multiple of number of elements to
*>* > replace in: x[c(1, NA, 3)] <- - (4:6)
*>* > > x
*>* > [1] -4 2 -5 4 5 6 7
*>* >
*>* > and NAs are ignored.
*>*
*>* Hmm. Neither of the options look too safe to me...
*>*
*>* A 3rd bit of logic would say that you should get a vector of
*>* 7 NAs since you're asking to put the -5 into an unknown location...
*>*
*>*
*
--
Brian D. Ripley, ripley@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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