[R-sig-eco] altitudinal overlap

[Stefano Leonardi]

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--
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  Stefano Leonardi
  Dipartimento di Bioscienze
  Universita` di Parma
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