subsetting a spatial polygons
Antonio, I am not sure why you think that your solution is not very elegant. In case you want to have more visual control over the subsetting, you could try mapedit: library(mapedit) myselection = selectFeatures(polys, mode = "draw") which will let you draw a e.g. rectangle and only return those features that intersect it. Best Tim
On 09/12/2018 04:18 AM, Antonio Silva wrote:
Dear list users
I have a SpatialPolygons with several squares. How to subset it to have
only the squares between given latitudes and longitudes?
In the example
library(sp)
library(raster)
grd <-
GridTopology(cellcentre.offset=c(-47.75,-25.416667),cellsize=c(10/60,10/60),cells.dim=c(23,12))
polys <- as.SpatialPolygons.GridTopology(grd)
proj4string(polys) <- CRS("+proj=longlat +datum=WGS84")
plot(polys,axes=T)
How to select only the squares, let's say, between 24-25?S and 45-46?W?
The farthest I went was:
e <- extent(-45.9,-45.1,-24.9,-24.1) # which is not very elegant
mask <- crop(polys,e)
polys2 <- polys[mask,]
plot(polys2,add=T,col="green")
Thanks a lot. Best regards