over-methods

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consistent spatial overlay for points, grids and polygons

consistent spatial overlay for points, grids and polygons: at the spatial locations of object x retrieves the indexes or attributes from spatial object y

Keywords
methods
Usage
over(x, y, returnList = FALSE, fn = NULL, ...)
x %over% y
## S3 method for class 'Spatial':
aggregate(x, by, FUN = mean, \dots)
Arguments
x
geometry (locations) of the queries
y
layer from which the geometries or attributes are queried
returnList
logical; see value
fn
(optional) a function; see value
by
geometry over which attributes in x are aggregated
FUN
aggregation function
...
arguments passed on to function fn or FUN
Value

  • an object of length length(x), or a data.frame with number of rows equal to length(x). If returnList is FALSE, a vector with the (first) index of y for each geometry (point, grid cell centre, polygon or lines) in x. if returnList is TRUE, a list of length length(x), with list element i the vector of all indices of the geometries in y that correspond to the $i$-th geometry in x.

    Function aggregate.Spatial aggregates the attribute values of x over the geometry of by, using aggregation function FUN.

Note

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

These methods assume that pixels and grid cells are never overlapping.

Methods that involve SpatialLines objects, or pairs of SpatialPolygons require, and are implemented in, package rgeos.

See Also

overlay, point.in.polygon

Aliases
  • over
  • %over%
  • over-methods
  • over,SpatialPoints,SpatialPoints-method
  • over,SpatialPoints,SpatialPointsDataFrame-method
  • over,SpatialPoints,SpatialPolygons-method
  • over,SpatialPoints,SpatialPolygonsDataFrame-method
  • over,SpatialGridDataFrame,SpatialPolygonsDataFrame-method
  • over,SpatialPolygons,SpatialPoints-method
  • over,SpatialPolygons,SpatialPointsDataFrame-method
  • over,SpatialGridDataFrame,SpatialPoints-method
  • over,SpatialGrid,SpatialPoints-method
  • over,SpatialPixelsDataFrame,SpatialPoints-method
  • over,SpatialPixels,SpatialPoints-method
  • over,SpatialPoints,SpatialGrid-method
  • over,SpatialPoints,SpatialGridDataFrame-method
  • over,SpatialPoints,SpatialPixels-method
  • over,SpatialPoints,SpatialPixelsDataFrame-method
  • over,SpatialPolygons,SpatialGridDataFrame-method
  • over,SpatialGrid,SpatialPolygons-method
  • over,SpatialGrid,SpatialPolygonsDataFrame-method
  • over,SpatialPolygons,SpatialGrid-method
  • aggregate.Spatial
Examples
r1 = cbind(c(180114, 180553, 181127, 181477, 181294, 181007, 180409, 
180162, 180114), c(332349, 332057, 332342, 333250, 333558, 333676, 
332618, 332413, 332349))
r2 = cbind(c(180042, 180545, 180553, 180314, 179955, 179142, 179437, 
179524, 179979, 180042), c(332373, 332026, 331426, 330889, 330683, 
331133, 331623, 332152, 332357, 332373))
r3 = cbind(c(179110, 179907, 180433, 180712, 180752, 180329, 179875, 
179668, 179572, 179269, 178879, 178600, 178544, 179046, 179110),
c(331086, 330620, 330494, 330265, 330075, 330233, 330336, 330004, 
329783, 329665, 329720, 329933, 330478, 331062, 331086))
r4 = cbind(c(180304, 180403,179632,179420,180304),
c(332791, 333204, 333635, 333058, 332791))

sr1=Polygons(list(Polygon(r1)),"r1")
sr2=Polygons(list(Polygon(r2)),"r2")
sr3=Polygons(list(Polygon(r3)),"r3")
sr4=Polygons(list(Polygon(r4)),"r4")
sr=SpatialPolygons(list(sr1,sr2,sr3,sr4))
srdf=SpatialPolygonsDataFrame(sr, data.frame(cbind(1:4,5:2), row.names=c("r1","r2","r3","r4")))

data(meuse)
coordinates(meuse) = ~x+y

plot(meuse)
polygon(r1)
polygon(r2)
polygon(r3)
polygon(r4)
# retrieve mean heavy metal concentrations per polygon:
over(sr, meuse[,1:4], fn = mean)

# return the number of points in each polygon:
sapply(over(sr, geometry(meuse), returnList = TRUE), length)

data(meuse.grid)
coordinates(meuse.grid) = ~x+y
gridded(meuse.grid) = TRUE

over(sr, geometry(meuse))
over(sr, meuse)
over(sr, geometry(meuse), returnList = TRUE)
over(sr, meuse, returnList = TRUE)

over(meuse, sr)
over(meuse, srdf)

# same thing, with grid:
over(sr, meuse.grid)
over(sr, meuse.grid, fn = mean)
over(sr, meuse.grid, returnList = TRUE)

over(meuse.grid, sr)
over(meuse.grid, srdf, fn = mean)
over(as(meuse.grid, "SpatialPoints"), sr)
over(as(meuse.grid, "SpatialPoints"), srdf)
Documentation reproduced from package sp, version 0.9-94, License: GPL (>= 2)

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