[R] data vector to corresonding percentile ranks
David Winsemius
dwinsemius at comcast.net
Fri Dec 23 18:23:33 CET 2011
On Dec 23, 2011, at 10:28 AM, Steve Jones wrote:
> I have a problem where I need to calculate the corresponding cohort
> percentile ranks for each of several variables.
>
> Essentially, what I need is a function that will calculate the
> distribution-free percentiles from each variable's data vector,
> returning a
> corresponding vector of percentiles:
>
> e.g.:
>
> percentile.my.data<-/function/(my.data)
>
>
> I tried to make ecdf() perform this task but was unsuccessful.
Unsuccessful? How? Seems like a reasonable strategy:
set.seed(123)
x <- rnorm(1000)
xCdist <- ecdf(x)
Seems to give sensible results.
> x[1]
[1] -0.7104066
> 100*xCdist(x[1])
[1] 23.4
> x[2]
[1] 0.2568837
> 100*xCdist(x[2])
[1] 60
>
> I'd be grateful for any help or advice...
My advice would be to post what code you were trying so that you can
get help understand what difficulties you need to overcome.
--
David Winsemius, MD
West Hartford, CT
More information about the R-help
mailing list