double bracket stripping names
On 26/02/2013 10:30, Patrick Burns wrote:
Is it on purpose that `[[` strips the names when used on an atomic vector?
Yes, and documented! It does when used on a list, so is consistent.
?"[["? can be used to select
a single element _dropping_ ?names?, whereas ?"["? keeps them,
e.g., in ?c(abc = 123)[1]?.
> c(a=1, b=2)[1]
a 1
> c(a=1, b=2)[[1]]
[1] 1
> sessionInfo()
R Under development (unstable) (2013-02-11 r61902) Platform: x86_64-w64-mingw32/x64 (64-bit) locale: [1] LC_COLLATE=English_United Kingdom.1252 [2] LC_CTYPE=English_United Kingdom.1252 [3] LC_MONETARY=English_United Kingdom.1252 [4] LC_NUMERIC=C [5] LC_TIME=English_United Kingdom.1252 attached base packages: [1] stats graphics grDevices utils datasets methods base
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