R help - Dec 2007 - R function for percentrank

Hi,

Does anyone know if R has a built-in function that is equvalent to Excel's
percentrank, i.e., returns the rank of a value in a data set as a percentage
of the data set?

Thanks,

-- 
Tom

	[[alternative HTML version deleted]]

I don't see one but that means nothing.   I think you
can write such a function in a few minutes

Will something like this work or am I
missunderstanding what Excel's percentrank does ?

aa <- rnorm(25);  aa  # data vector 
percentrank <- function(x) { 
var  <- sort(x)
p.rank <- 1:length(var)/length(var)*100
dd  <- cbind(var,p.rank)
}
pr <- percentrank(aa); pr


--- tom soyer <tom.soyer at gmail.com> wrote:
> Hi,
> 
> Does anyone know if R has a built-in function that
> is equvalent to Excel's
> percentrank, i.e., returns the rank of a value in a
> data set as a percentage
> of the data set?
> 
> Thanks,
> 
> -- 
> Tom
> 
> 	[[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.
>

Its a bit tricky if you want to get it to work exactly the same as
Excel even in the presence of runs but in terms of the R approx function
I think percentrank corresponds to ties = "min" if the value is among
those
in the table and ties = "ordered" otherwise so:

percentrank <- function(table, x = table) {
   table <- sort(table)
   ties <- ifelse(match(x, table, nomatch = 0), "min",
"ordered")
   len <- length(table)
   f <- function(x, ties)
      (approx(table, seq(0, len = len), x, ties = ties)$y) / (len - 1)
   mapply(f, x, ties)
}

# test
tab <- c(1, 1, 2, 2, 3, 3)
percentrank(tab, 2:6/2) # c(0, .3, .4, .7, .8)

which is the same result as Excel 2007 gives.

On Dec 1, 2007 6:37 AM, tom soyer <tom.soyer at gmail.com>
wrote:
> Hi,
>
> Does anyone know if R has a built-in function that is equvalent to
Excel's
> percentrank, i.e., returns the rank of a value in a data set as a
percentage
> of the data set?
>
> Thanks,
>
> --
> Tom
>
>        [[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.
>