altitudinal overlap

The first think that came to my mind:

overlap <- function(v1,v2) {
ov <-min(max(v1), max(v2)) - max(min(v1), min(v2))
ifelse(ov > 0, ov, 0)
}

overlap(dat[1,], dat[2,])
[1] 0.5


Ciao
Stefano

On 14/07/2015 01:03, Karla Shikev wrote:

Hi there,

This is a newbie question, and I'm sure there are simple ways to do this,
but I've spent my entire afternoon and I couldn't get it to work.

Imagine that I got the altitudinal range of different species. For
instance:

 dat<-matrix(c(1,3,2.5,4), ncol=2, byrow=TRUE)

dat

      [,1] [,2]
[1,]  1.0    3
[2,]  2.5    4


The first line indicates that this species is found between 1 and 3,
whereas the second species was found between 2.5 and 4.

I need a simple way to calculate the overlap of their extents (0.5 in this
case). This way should provide 0 if there is no overlap, and it should
also
work in the case where one subject is found only within the extent of the
second subject.

Any help will be greatly appreciated.

Karla--

======================================================================
 Stefano Leonardi
 Dipartimento di Bioscienze
 Universita` di Parma
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 43124 PARMA  (Italy)                          Fax   : +39-0521-905402

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