[R] custom sort?
murdoch at stats.uwo.ca
Fri May 29 03:38:23 CEST 2009
On 28/05/2009 8:17 PM, Stavros Macrakis wrote:
> I couldn't get your suggested method to work:
> `==.foo` <- function(a,b) unclass(a)==unclass(b)
> `>.foo` <- function(a,b) unclass(a) < unclass(b) # invert comparison
> is.na.foo <- function(a)is.na(unclass(a))
> sort(structure(sample(5),class="foo")) #-> 1:5 -- not reversed
> What am I missing?
I'm not sure: I've never actually used that, I was basing it on the
docs. Looks like it's not as simple as I thought. Sorry for the
> On Thu, May 28, 2009 at 5:48 PM, Duncan Murdoch <murdoch at stats.uwo.ca>wrote:
>> On 28/05/2009 5:34 PM, Steve Jaffe wrote:
>>> Sounds simple but haven't been able to find it in docs: is it possible to
>>> sort a vector using a user-defined comparison function? Seems it must be,
>>> but "sort" doesn't seem to provide that option, nor does "order" sfaics
>> You put a class on the vector (e.g. using class(x) <- "myvector"), then
>> define a conversion to numeric (e.g. xtfrm.myvector) or actual comparison
>> methods (you'll need ==.myvector, >.myvector, and is.na.myvector).
>> Duncan Murdoch
>> R-help at r-project.org mailing list
>> PLEASE do read the posting guide
>> and provide commented, minimal, self-contained, reproducible code.
More information about the R-help