Class "SpatialGridDataFrame"

Description

Class for spatial attributes that have spatial locations on a (full) regular grid.

Objects from the Class

Objects can be created by calls of the form as(x, "SpatialGridDataFrame"), where x is of class SpatialPixelsDataFrame-class, or by importing through rgdal. Ordered full grids are stored instead or unordered non-NA cells;

Slots

coords:

see SpatialPoints; points slot which is not actually filled with all coordinates (only with min/max)

grid:

see GridTopology-class; grid parameters

grid.index:

see SpatialPixels-class; this slot is of zero length for this class, as the grid is full

bbox:

Object of class "matrix"; bounding box

proj4string:

Object of class "CRS"; projection

data:

Object of class data.frame, containing attribute data

Extends

Class "SpatialGrid", directly. Class "Spatial", by class "SpatialGrid".

Methods

coordinates

signature(x = "SpatialGridDataFrame"): retrieves (and calculates!) coordinates

[

signature(x = "SpatialGridDataFrame"): selects rows, columns, and attributes; returns an object of class SpatialGridDataFrame

as.matrix

signature(x = "SpatialGridDataFrame"): coerce to matrix

cbind

signature(...): if arguments have identical topology, combine their attribute values

Author(s)

Edzer Pebesma, edzer.pebesma@uni-muenster.de

See Also

SpatialGrid-class, which does not contain the attribute data, and SpatialPixelsDataFrame-class which holds possibly incomplete grids

Examples

data(meuse.grid) # only the non-missing valued cells
coordinates(meuse.grid) = c("x", "y") # promote to SpatialPointsDataFrame
gridded(meuse.grid) <- TRUE # promote to SpatialPixelsDataFrame
x = as(meuse.grid, "SpatialGridDataFrame") # creates the full grid
x[["idist"]] = 1 - x[["dist"]] # assigns new attribute
image(x["idist"]) # note the single [ for attribute selection

# toy example:
df = data.frame(z = c(1:6,NA,8,9),
    xc = c(1,1,1,2,2,2,3,3,3),
    yc = c(rep(c(0, 1.5, 3),3)))
coordinates(df) = ~xc+yc
gridded(df) = TRUE
df = as(df, "SpatialGridDataFrame") # to full grid
image(df["z"])
# draw labels to verify:
cc = coordinates(df)
z=df[["z"]]
zc=as.character(z)
zc[is.na(zc)]="NA"
text(cc[,1],cc[,2],zc)

# the following is weird, but illustrates the concept of row/col selection:
fullgrid(meuse.grid) = TRUE
image(meuse.grid)
image(meuse.grid[20:70, 10:70, "dist"], add = TRUE, col = bpy.colors())