Dear Claire,
The below function uses a raster to stratify the region.
You can tune it by changing the resolution of the raster (res) and/or
n (the number of samples to take from each cell).
library(raster)
gridsample <- function(xy, res, n=1) {
r = raster(extent(range(xy[,1]), range(xy[
Dear all,
I am carrying out some species distribution modelling based on a database of
species occurrence records of a single tree species, encompassing the entire
European
continent. The records are primarily historical and heavily biased towards
western, northern Europe. A few of the counts of
