On Jan 11, 2012, at 8:12 AM, Martin Batholdy wrote:

Hi,

I have a vector with values:

x <- rnorm(1000, 5, 2)

and one single value:

y <- 6.2

now I would like to know the percent rank of y based on the

'population'-vector x.

Is there a convenient function that calculates the percent rank of a

y for the given vector x?

Two options :

1) sort x and use findInterval, divide the index by length(x) and

multiply by 100

(It can all be done as a one-liner.)

2) I generally "reach for" the `ecdf` "function making machine" when I

see sample quantile problems and see if I can cast the problem in

terms for which it applies.

For my random draw I get:

findInterval(6.2, sort(x)) [1] 704

xecdf <- ecdf(x)

xecdf(6.2)

[1] 0.704

--

David Winsemius, MD

West Hartford, CT