[Rd] R Language Definition: Subsetting matrices with negative indices is *not* an error

Henrik Bengtsson
2015-05-09T00:53:15Z

Hi,

I spotted what looks like another(*) mistake in 'R Language
Definition' on how subsetting should work.  In Section 'Indexing
matrices and arrays'
[http://cran.r-project.org/doc/manuals/r-release/R-lang.html#Indexing-matrices-and-arrays]
one can read

   "Negative indices are not allowed in indexing matrices."

but this is not true, e.g.

> x <- matrix(1:12, nrow=4)
> x
     [,1] [,2] [,3]
[1,]    1    5    9
[2,]    2    6   10
[3,]    3    7   11
[4,]    4    8   12

> x[c(-2,-4),]
     [,1] [,2] [,3]
[1,]    1    5    9
[2,]    3    7   11

/Henrik

(*) https://stat.ethz.ch/pipermail/r-devel/2015-May/071091.html [docs
have been fixed]