GDALReadOnlyDataset-class {rgdal} | R Documentation |
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) 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)
dataset |
An object inheriting from class 'GDALReadOnlyDataset' |
filename |
A string giving the file to read from |
x |
An object inheriting from class 'GDALReadOnlyDataset' |
offset |
Number of rows and columns from the origin (usually the upper left corner) to begin reading from |
region.dim |
The number of rows and columns to read from the dataset |
reduction |
scaling parameter for region.dim |
band |
The band number (1-based) to read from |
col |
a vector of colours or a colour function such as rainbow |
max.dim |
another scaling parameter |
... |
other plotting parameters passed through |
|
|
|
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'.
displayDataset
and its use in plot
for a pixmap object to produce a plot of the dataset, returning a pixmap object.
getColorTable
returns the dataset colour table (currently does not support RGB imaging).
getGeoTransFunc
returns a warping function.
Objects can be created by calls of the form new("GDALReadOnlyDataset", filename, handle)
.
~~ describe objects here ~~
handle
:"externalptr", from class "GDALMajorObject"
~~
Class "GDALMajorObject"
, directly.
signature(dataset = "GDALReadOnlyDataset")
: ... signature(x = "GDALReadOnlyDataset")
: ... signature(.Object = "GDALReadOnlyDataset")
: ... Timothy H. Keitt, modified by Roger Bivand
http://keittlab.bio.sunysb.edu/R/GDAL/, http://www.remotesensing.org/gdal/
See also GDALDriver-class
, GDALDataset-class
, GDALTransientDataset-class
.
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)