[R] rank with uniform count for each rank

[David Winsemius]

On Feb 22, 2012, at 4:01 PM, Ben quant wrote:

> Hello,
>
> What is the best way to get ranks for a vector of values, limit the  
> range
> of rank values and create equal count in each group? I call this  
> uniform
> ranking...uniform count/number in each group.
>
> Here is an example using three groups:
>
> Say I have values:
> x = c(3, 2, -3, 1, 0, 5, 10, 30, -1, 4)
> names(x) = letters[1:10]
>> x
> a  b  c  d  e  f   g   h   i   j
> 3  2 -3  1  0  5 10 30 -1  4
> I would like:
> a  b  c  d  e  f  g  h  i  j
> 2  2  1  2  1  3 3  3  1 3
>
> Same thing as above, maybe easier to see:
> c   i  e  d  b  a   j   f  g   h
> -3 -1  0  1  2  3  4  5 10 30
> I would get:
> c  i e d b a  j f  g h
> 1 1 1 2 2 2 3 3 3 3
>
> Note that there are 4 values with a rank of 3 because I can't get even
> numbers (10/3 = 3.333).
>
> Been to ?sort, ?order, ?quantile, ?cut, and ?split.

You may need to look more carefully at the definitions and adjustments  
to `cut` and `quantile` but this does roughly what you asked:

n=3
as.numeric( cut(x, breaks=quantile(x, prob=(0:n)/n) ,  
include.lowest=TRUE) )
@ [1] 1 1 1 1 2 2 2 3 3 3

It a fairly common task and Harrell's cut2 function has a g= parameter  
(for number of groups)  that I generally use:

library(Hmisc)
 >  cut2(x, g=3)
  [1] [-3, 2) [-3, 2) [-3, 2) [-3, 2) [ 2, 5) [ 2, 5) [ 2, 5) [ 5,30]  
[ 5,30] [ 5,30]
Levels: [-3, 2) [ 2, 5) [ 5,30]
 >  as.numeric( cut2(x, g=3))
  [1] 1 1 1 1 2 2 2 3 3 3



>
> Thanks,
>
> Ben
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT