GDALReadOnlyDataset-class.Rd
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
.
GDAL.close(dataset)
GDAL.open(filename, read.only = TRUE, silent=FALSE,
allowedDrivers = NULL, options=NULL)
getDriver(dataset)
<!-- %displayDataset(x, offset = c(0, 0), region.dim = dim(x), -->
<!-- % reduction = 1, band = NULL, col = NULL, -->
<!-- % max.dim = 500, ...) -->
getColorTable(dataset, band = 1)
getGeoTransFunc(dataset)
Objects can be created by calls of the form new("GDALReadOnlyDataset", filename, handle)
.
~~ describe objects here ~~
handle
:Object of class "externalptr", from class "GDALMajorObject"
~~
Class "GDALMajorObject"
, directly.
signature(dataset = "GDALReadOnlyDataset")
: ...
signature(x = "GDALReadOnlyDataset")
: ...
signature(.Object = "GDALReadOnlyDataset")
: ...
An object inheriting from class 'GDALReadOnlyDataset'
name of file to contain raster data object; will be normalized with normalizePath
if it is a file
The band number (1-based) to read from
A logical flag indicating whether to open the file as a
GDALReadOnlyDataset
or as a writable GDALDataset
logical; if TRUE, comment and non-fatal CPL driver errors suppressed
a character vector of suggested driver short names may be provided starting from GDAL 2.0
open options may be passed to raster drivers starting from GDAL 2.0; very few drivers support these options
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.
logo <- system.file("pictures/logo.jpg", package="rgdal")[1]
x <- new("GDALReadOnlyDataset", logo)
dim(x)
#> [1] 175 200
plot(density(getRasterTable(x)$band1))
#> Warning: GeoTransform values not available
#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)
#> [1] 175 200 3
#displayDataset(x)
GDAL.close(x)