> On 09 May 2015, at 02:53 , Henrik Bengtsson <henrik.bengts...@ucsf.edu> wrote:
>
> 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."
Parse error: I believe that this is intended to mean
"Indexing matrices may not contain negative indices"
not
"You cannot use negative indices when indexing matrices".
This is consistent with the help page:
"
A third form of indexing is via a numeric matrix with the one
column for each dimension: each row of the index matrix then
selects a single element of the array, and the result is a vector.
Negative indices are not allowed in the index matrix.
"
Rephrasing would seem to be in order....
-pd
>
> 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]
>
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--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd....@cbs.dk Priv: pda...@gmail.com
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