On 12/16/2009 12:14 AM, Peter Dalgaard wrote:
Romain Francois wrote:
Hello,
I very much enjoy "with" and "subset" semantics for data frames and
was wondering if we could have something similar with split, basically
by evaluating the second argument "with" the data frame :
I seem to recall that this idea was considered and rejected when the
current split.data.frame was written (10 years ago!). The main reasons
were that
- it's not really THAT hard to evaluate a single splitting expression
using with() or eval()
Sure, this is just about convenience and laziness.
- not all applications will have the splitting factor inside the df to
split ( split(df[-1], df[[1]]) for a simple case)
this still works
- if you need a computed splitting factor, there's a risk of inadvertent
variable capture. I.e., if you inside a function do
....
grp <- ...whatever...
spl <- split(x, grp)
....
and x has a variable called grp, what do you get?
this is a problem indeed.
thanks for the reply.
Romain
--
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr
|- http://tr.im/HlX9 : new package : bibtex
|- http://tr.im/Gq7i : ohloh
`- http://tr.im/FtUu : new package : highlight
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
