Selecting Random Polygons
require(sp) # select 20 random polygons: nysample = nylakes[sample(4466,20),] plot(nysample) # sample a single random point inside each polygon: pts = do.call(rbind, lapply(nysample at polygons, spsample, n=1, type="random")) plot(p, add=TRUE, col='red') hth,
On 03/21/2014 02:30 PM, Robin Sleith wrote:
Hello, I have a set of spatial polygons (nylakes) and I would like to randomly select a number of polygons from nylakes. I do not need an output file of polygons necessarily, just a set of points would do. I have tried spsample, but it places multiple points per polygon, even when stratified is selected. Any thoughts? Info below. Thank you Robin
nylakes
class : SpatialPolygons features : 4466 extent : -80, -71.88637, 40.29375, 45.48771 (xmin, xmax, ymin, ymax) coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0 twenty <- spsample(nylakes, 20, type='random') twenty <- spsample(nylakes, 20, type='stratified') [[alternative HTML version deleted]]
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