(numeric) number of survey points (sites) to be
selected.
space
(character) space in which the thinning will be performed. There
are two options available: "G", if it will be in geographic space, and
"E", if it will be in environmental space.
variable_1
(character or numeric) name or position of the first
variable (x-axis). Default = NULL.
variable_2
(character or numeric) name or position of the second
variable (y-axis). Default = NULL.
use_blocks
(logical) whether or not to use block centroids instead of
all points when space = "E". Default = FALSE.
verbose
(logical) whether or not to print messages about the process.
Default = TRUE.
Value
A list of two elements: the distance used to obtain expected_points
and a SpatialPolygonsDataFrame object created from preselected_sites in
master.