R help - Jun 2004 - alternate rank method

Hi,

I'm wondering if anyone can point me to a function that will
allow me to do a ranking that treats ties differently than
rank() provides for?

I'd like a method that will assign to the elements of each 
tie group the largest rank. 

An example:  

For the vector 'v', I'd like the method to return 'rv'

 v:  1 2 3 3 3 4 5 5 6 7
rv:  1 2 5 5 5 6 8 8 9 10


Thanks,
Doug Grove

Douglas Grove wrote:
> Hi,
> 
> I'm wondering if anyone can point me to a function that will
> allow me to do a ranking that treats ties differently than
> rank() provides for?
> 
> I'd like a method that will assign to the elements of each 
> tie group the largest rank. 
> 
> An example:  
> 
> For the vector 'v', I'd like the method to return 'rv'
> 
>  v:  1 2 3 3 3 4 5 5 6 7
> rv:  1 2 5 5 5 6 8 8 9 10
> 
> 
> Thanks,
> Doug Grove
> 
How about

rv <- rowSums(outer(v, v, ">="))

Adapted from Prof. Ripley's reply in the following thread:

http://finzi.psych.upenn.edu/R/Rhelp02/archive/31993.html

HTH,

--sundar

Here are a couple of solutions:

rx <- rank(x)
order(-order(rev(x)))[match(rx,rx)]

rx <- rank(x)
(2*rx-rank(x,tie="first"))[match(rx,rx)]


Douglas Grove <dgrove <at> fhcrc.org> writes:

: 
: Hi,
: 
: I'm wondering if anyone can point me to a function that will
: allow me to do a ranking that treats ties differently than
: rank() provides for?
: 
: I'd like a method that will assign to the elements of each 
: tie group the largest rank. 
: 
: An example:  
: 
: For the vector 'v', I'd like the method to return 'rv'
: 
:  v:  1 2 3 3 3 4 5 5 6 7
: rv:  1 2 5 5 5 6 8 8 9 10
: 
: 
: Thanks,
: Doug Grove

Try:


MxRank <- function(x, na.last = "keep")
{
         if (na.last != "keep")
                 return(rank(x, na.last))
         else {
                 r <- x*NA
                 NoWarn(r[is.orderable(x)] <- rank(x,na.last=NA))
                 return(r)
} }


Knut M. Wittkowski, PhD,DSc
------------------------------------------
The Rockefeller University, GCRC
Experimental Design and Biostatistics
1230 York Ave #121B, Box 322, NY,NY 10021
+1(212)327-7175, +1(212)327-8450 (Fax)
kmw at rockefeller.edu
http://www.rucares.org/clinicalresearch/dept/biometry/