overlay-methods {sp} | R Documentation

## Methods for spatially overlay-ing points (grids) and rings layers

### Description

overlay combines points (or grids) and rings by performing point-in-polygon operation on all point-ring combinations.

### Methods

x = "SpatialPoints", y = "SpatialPolygons"
  returns a numeric vector of length equal to the number of points; the number is the id (number) of the ring of `y` in which a point falls; NA denotes the point does not fall in a ring; if a point falls in multiple rings, the last ring is recorded.
x = "SpatialPointsDataFrame", y = "SpatialPolygons"
  equal to the previous method, except that an argument `fn=xxx` is allowed, e.g. `fn = mean` which will then report a data.frame with the mean values of the `x` points fallin in each ring (set) of `y`
x = "SpatialPolygons", y = "SpatialPoints"
  returns the ring id of points in `y`; if `x` is a `SpatialRingDataFrame`, a data.frame with rows from `x` corresponding to ponits in `y` is returned.
x = "SpatialGridDataFrame", y = "SpatialPoints"
  returns object of class SpatialPointsDataFrame with grid attribute values x at spatial point locations y; NA for NA grid cells or points outside grid, and NA values on NA grid cells.
x = "SpatialGrid", y = "SpatialPoints"
  returns grid values x at spatial point locations y; NA for NA grid cells or points outside the grid
x = "SpatialPixelsDataFrame", y = "SpatialPoints"
  returns grid values x at spatial point locations y; NA for NA grid cells or points outside the grid
x = "SpatialPixels", y = "SpatialPoints"
  returns grid values x at spatial point locations y; NA for NA grid cells or points outside the grid

### Note

points on a ring boundary and points corresponding to a ring vertex are considered to be inside the ring

### Author(s)

Edzer J. Pebesma, e.pebesma@geo.uu.nl

### See Also

overlay, point.in.polygon

[Package sp version 0.7-12 Index]