p1 = Polygon(cbind(c(2,4,4,1,2),c(2,3,5,4,2)))
p2 = Polygon(cbind(c(5,4,2,5),c(2,3,2,2)))
p3 = Polygon(cbind(c(4,4,5,10,4),c(5,3,2,5,5)))

P1 = Polygons(list(p1), "s1")
P2 = Polygons(list(p2), "s2")
P3 = Polygons(list(p3), "s3")
SP = SpatialPolygons(list(P1,P2,P3), 1:3)