rgdal (version 0.7-7)

GDALReadOnlyDataset-class: Class "GDALReadOnlyDataset"

Description

GDALReadOnlyDataset is the base class for a GDAL Dataset classes. Only read operations are supported. Both GDALDataset and GDALTransientDataset inherit these read operations while providing additional write operations (see GDALDataset-class). GDALReadOnlyDataset-class inherits from GDALMajorObject-class.

Usage

GDAL.close(dataset)
GDAL.open(filename, read.only = TRUE, silent=FALSE)
getDriver(dataset)getColorTable(dataset, band = 1)
getGeoTransFunc(dataset)

Arguments

dataset

An object inheriting from class 'GDALReadOnlyDataset'

filename

A string giving the file to read from

band

The band number (1-based) to read from

read.only

A logical flag indicating whether to open the file as a GDALReadOnlyDataset or as a writable GDALDataset

silent

logical; if TRUE, comment and non-fatal CPL driver errors suppressed

Objects from the Class

Objects can be created by calls of the form new("GDALReadOnlyDataset", filename, handle). ~~ describe objects here ~~

Extends

Class "GDALMajorObject", directly.

Details

GDAL.open and GDAL.close are shorter versions of new("GDALReadOnlyDataset", ...) and closeDataset(). Because GDAL.close through closeDataset() uses the finalization mechanism to destroy the handles to the dataset and its driver, messages such as:

"Closing GDAL dataset handle 0x8ff7900... destroyed ... done."

may appear when GDAL.close is run, or at some later stage. getDriver returns an object inheriting from class 'GDALDriver'.getColorTable returns the dataset colour table (currently does not support RGB imaging). getGeoTransFunc returns a warping function.

References

http://www.keittlab.org/, http://www.gdal.org/

See Also

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

Examples

logo <- system.file("pictures/logo.jpg", package="rgdal")[1]
x <- new("GDALReadOnlyDataset", logo)
dim(x)
plot(density(getRasterTable(x)$band1))
#displayDataset(x)
#displayDataset(x, col=function(x){rev(cm.colors(x))})
#im <- displayDataset(x, col=function(x){rev(cm.colors(x))}, reset.par=FALSE)
#contour(1:attr(im, "size")[2], 1:attr(im, "size")[1],
# t(attr(im, "index"))[,attr(im, "size")[1]:1], nlevels = 1,
# levels = 100, col = 'black', add = TRUE)
GDAL.close(x)
logo <- system.file("pictures/Rlogo.jpg", package="rgdal")[1]
x <- new("GDALReadOnlyDataset", logo)
dim(x)
#displayDataset(x)
GDAL.close(x)