split() - unexpected sorting of results
Hi,
On 10/20/2017 12:53 PM, Peter Meissner wrote:
Thanks, for the explanation. Still, I think this is surprising bahaviour which might be handled better.
Maybe a little surprising, but no more than: > x <- sample(11L) > sort(x) [1] 1 2 3 4 5 6 7 8 9 10 11 > sort(as.character(x)) [1] "1" "10" "11" "2" "3" "4" "5" "6" "7" "8" "9" The fact that sort(), as.factor(), split() and many other things behave consistently with respect to the underlying order of character vectors avoids other even bigger surprises. Also note that the underlying order of character vectors actually depends on your locale. One way to guarantee consistent results across platforms/locales is by explicitly specifying the levels when making a factor e.g. f <- factor(x, levels=unique(x)) split(1:11, f) This is particularly sensible when writing unit tests. Cheers, H.
Best, Peter Am 20.10.2017 9:49 nachm. schrieb "I?aki ?car" <i.ucar86 at gmail.com>:
Hi Peter, 2017-10-20 21:33 GMT+02:00 Peter Meissner <retep.meissner at gmail.com>:
Hey, I found this - for me - quite surprising and puzzling behaviour of
split().
split(1:11, as.character(1:11)) split(1:11, 1:11) When splitting by numerics everything works as expected - sorting of
input
== sorting of output -- but when using a character vector everything gets re-sorted alphabetical. Although, there are some references in the help files to what happens
when
using split, I did not find any note on this - for me - rather unexpected behaviour.
As the documentation states,
f: a ?factor? in the sense that ?as.factor(f)? defines the
grouping, or a list of such factors in which case their
interaction is used for the grouping.
And, in fact,
as.factor(1:11)
[1] 1 2 3 4 5 6 7 8 9 10 11 Levels: 1 2 3 4 5 6 7 8 9 10 11
as.factor(as.character(1:11))
[1] 1 2 3 4 5 6 7 8 9 10 11 Levels: 1 10 11 2 3 4 5 6 7 8 9 Regards, I?aki
I would like it best when the sorting of split results stays the same no
matter the input (sorting of input == sorting of output)
If that is not possibly a note of caution in the help pages and maybe an
example might be valuable.
Best, Peter
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