Generate sampling points within a SpatialPolygon object, according to a specified sampling density.
sample.by.poly(p, n.pts.per.ac=1, min.samples=5,
sampling.type='regular', iterations=10, p4s=NULL)a Polygon object, with coordinates in a projected CRS with units of meters
requested sampling density in points per acre (results will be close)
minimum requested number of samples per polygon
sampling type, see spsample
number of tries that spsample will attempt
a qualified proj4string that will be assigned to sampling points
A SpatialPoints object.
This function is typically accessed via some kind of helper function such as constantDensitySampling.