nicheOverlap
Niche overlap
Compute niche overlap from predictions of species distributions with the 'I' or 'D' similarity statistic of Warren et al. (2009). The statistic ranges from 0 (no overlap) to 1 (the distributions are identical).
Usage
nicheOverlap(x, y, stat='I', mask=TRUE, checkNegatives=TRUE)
Arguments
- x
RasterLayer with non-negative values (predictions of the probability that a site is suitable for a species)
- y
RasterLayer with non-negative values, as above
- stat
character either 'I' or 'D' to get the statistic with that name
- mask
logical. If
TRUE
the function removes cells fromx
that areNA
iny
and vice-versa. If you are sure that such cases do not occur you can set this toFALSE
to speed up computations- checkNegatives
logical. If
TRUE
the function checks of any of the values inx
andy
are negative. If you are sure that such cases do not occur you can set this toFALSE
to speed up computations
Value
numeric
References
Warren, D.L., R.E. Glor, M. Turelli, and D. Funk. 2009. Environmental niche equivalency versus conservatism: quantitative approaches to niche evolution. Evolution 62:2868-2883; Erratum: Evolution 65: 1215
Examples
# NOT RUN {
r1 <- raster(nr=18, nc=36)
r2 <- raster(nr=18, nc=36)
set.seed(0)
r1[] <- runif(ncell(r1))
r2[] <- runif(ncell(r1))
nicheOverlap(r1, r2)
# }