subset methods for "GDALReadOnlyDataset"

Description

subsets GDAL objects, returning a SpatialGridDataFrame object

Details

The [ method subsets a GDAL data set, returning a SpatialGridDataFrame object. Reading is done on the GDAL side, and only the subset requested is ever read into memory.

Further named arguments to [ are to either getRasterTable or getRasterData:

as.is

see getRasterData

interleave

see getRasterData

output.dim

see getRasterData

the other arguments, offset and region.dim are derived from row/column selection values.

An GDALReadOnlyDataset object can be coerced directly to a SpatialGridDataFrame

Methods

"["

signature(.Object = "GDALReadOnlyDataset"): requires package sp; selects rows and columns, and returns an object of class SpatialGridDataFrame if the grid is not rotated, or else of class SpatialPointsDataFrame. Any arguments passed to getRasterData (or in case of rotation getRasterTable) may be passed as named arguments; the first three unnamed arguments are row,col,band

Author(s)

Edzer Pebesma

See Also

See also readGDAL GDALDriver-class, GDALDataset-class, GDALTransientDataset-class, SpatialGridDataFrame-class .

Examples

library(grid)
logo <- system.file("pictures/logo.jpg", package="rgdal")[1]
x <- new("GDALReadOnlyDataset", logo)
dim(x)
x.sp = x[20:50, 20:50]
class(x.sp)
summary(x.sp)
spplot(x.sp)
GDAL.close(x)

logo <- system.file("pictures/Rlogo.jpg", package="rgdal")[1]
x.gdal <- new("GDALReadOnlyDataset", logo)
x = x.gdal[,,3]
dim(x)
summary(x)
spplot(x)
spplot(x.gdal[])
GDAL.close(x.gdal)

logo <- system.file("pictures/Rlogo.jpg", package="rgdal")[1]
x.gdal <- new("GDALReadOnlyDataset", logo)
x.as <- as(x.gdal, "SpatialGridDataFrame")
GDAL.close(x.gdal)
summary(x.as)