[R] custom sort?

[Duncan Murdoch]

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 
misinformation.

Duncan Murdoch

> 
>            -s
> 
> 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
>>
>>
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>