polygons {sp}

sets spatial coordinates to create spatial data, or retrieves spatial coordinates

Description

sets spatial coordinates to create spatial data, or retrieves spatial coordinates

Usage

	polygons(obj)
	polygons(object) <- value

Arguments

obj

object of class "SpatialPolygons" or "SpatialPolygonsDataFrame"

object

object of class "data.frame"

value

object of class "SpatialPolygons"

Value

polygons returns the SpatialPolygons of obj; polygons<- promotes a data.frame to a SpatialPolygonsDataFrame object

Examples

grd <- GridTopology(c(1,1), c(1,1), c(10,10))
polys <- as.SpatialPolygons.GridTopology(grd)
centroids <- coordinates(polys)
x <- centroids[,1]
y <- centroids[,2]
z <- 1.4 + 0.1*x + 0.2*y + 0.002*x*x
df <- data.frame(x=x, y=y, z=z, row.names=row.names(polys))
polygons(df) <- polys
class(df)
summary(df)