brick {raster} | R Documentation |
A RasterBrick is a multi-layer raster object. They are typically created from a multi-layer (band) file; but they can also exist entirely in memory. They are similar to a RasterStack (that can be created with stack
), but processing time should be shorter when using a RasterBrick. Yet they are less flexible as they can only point to a single file.
A RasterBrick can be created from RasterLayer objects, from a RasterStack, or from a (multi-layer) file. The can also be created from SpatialPixels*, SpatialGrid*, and Extent objects, and from a three-dimensional array.
## S4 method for signature 'character' brick(x, ...) ## S4 method for signature 'RasterStack' brick(x, values=TRUE, nl, filename='', ...) ## S4 method for signature 'RasterBrick' brick(x, nl, ...) ## S4 method for signature 'RasterLayer' brick(x, ..., values=TRUE, nl=1, filename='') ## S4 method for signature 'missing' brick(nrows=180, ncols=360, xmn=-180, xmx=180, ymn=-90, ymx=90, nl=1, crs) ## S4 method for signature 'Extent' brick(x, nrows=10, ncols=10, crs=NA, nl=1) ## S4 method for signature 'array' brick(x, xmn=0, xmx=1, ymn=0, ymx=1, crs=NA, transpose=FALSE) ## S4 method for signature 'big.matrix' brick(x, template, filename='', ...) ## S4 method for signature 'SpatialGrid' brick(x) ## S4 method for signature 'SpatialPixels' brick(x)
x |
character (filename, see Details); Raster* object; missing; array; SpatialGrid*; SpatialPixels*; Extent; or list of Raster* objects. Supported file types are the 'native' raster package format and those that can be read via rgdal (see |
... |
see Details |
values |
logical. If |
nl |
integer > 0. How many layers should the RasterBrick have? |
filename |
character. Filename if you want the RasterBrick to be saved on disk |
nrows |
integer > 0. Number of rows |
ncols |
integer > 0. Number of columns |
xmn |
minimum x coordinate (left border) |
xmx |
maximum x coordinate (right border) |
ymn |
minimum y coordinate (bottom border) |
ymx |
maximum y coordinate (top border) |
crs |
character or object of class CRS. PROJ4 type description of a Coordinate Reference System (map projection). If this argument is missing, and the x coordinates are withing -360 .. 360 and the y coordinates are within -90 .. 90, "+proj=longlat +datum=WGS84" is used |
transpose |
if |
template |
Raster* object used to set the extent, number of rows and columns and CRS |
If x
is a RasterLayer, the additional arguments can be used to pass additional Raster* objects.
If there is a filename
argument, the additional arguments are as for writeRaster
. The big.matrix most have rows representing cells and columns representing layers.
If x
represents a filename there is the following additional argument:
native
: logical. If TRUE
(not the default), reading and writing of IDRISI, BIL, BSQ, BIP, and Arc ASCII files is done with native (raster package) drivers, rather then via rgdal.
In addition, if x
is a NetCDF filename there are the following additional arguments:
varname
: character. The variable name (e.g. 'altitude' or 'precipitation'. If not supplied and the file has multiple
variables are a guess will be made (and reported))
lvar
: integer > 0 (default=3). To select the 'level variable' (3rd dimension variable) to use, if the file has 4 dimensions (e.g. depth instead of time)
level
: integer > 0 (default=1). To select the 'level' (4th dimension variable) to use, if the file has 4 dimensions, e.g. to create a RasterBrick of weather over time at a certain height.
To use NetCDF files the ncdf
or the ncdf4
package needs to be available. If both are available, ncdf4
is used. Only the ncdf4
package can read the most recent version (4) of the netCDF format (as well as older versions), for windows it not available on CRAN but can be downloaded here. It is assumed that these files follow, or are compatible with the CF convention.
RasterBrick
b <- brick(system.file("external/rlogo.grd", package="raster")) b nlayers(b) names(b) extract(b, 870)