R help - Oct 2013 - Extracting values from a ecdf (empirical cumulative distribution function) curve

Hi R users,

I am a new user, still learning basics of R. Is there anyway to extract y
(or x) value for a known x (or y) value from ecdf (empirical cumulative
distribution function) curve?

Thanks in advance.
Mano.

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Hello,

As for the problem of finding y given the ecdf and x, it's very easy, 
just use the ecdf:

f <- ecdf(rnorm(100))

x <- rnorm(10)
y <- f(x)

If you want to get the x corresponding to given y, use linear interpolation.

inv_ecdf <- function(f){
	x <- environment(f)$x
	y <- environment(f)$y
	approxfun(y, x)
}

g <- inv_ecdf(f)
g(0.5)


Hope this helps,

Rui Barradas

Em 31-10-2013 12:25, Manoranjan Muthusamy escreveu:
> Hi R users,
>
> I am a new user, still learning basics of R. Is there anyway to extract y
> (or x) value for a known x (or y) value from ecdf (empirical cumulative
> distribution function) curve?
>
> Thanks in advance.
> Mano.
>
> 	[[alternative HTML version deleted]]
>
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