gdalraster (version 1.11.1)

rasterFromRaster: Create a raster from an existing raster as template

Description

rasterFromRaster() creates a new raster with spatial reference, extent and resolution taken from a template raster, without copying data. Optionally changes the format, number of bands, data type and nodata value, sets driver-specific dataset creation options, and initializes to a value.

Usage

rasterFromRaster(
  srcfile,
  dstfile,
  fmt = NULL,
  nbands = NULL,
  dtName = NULL,
  options = NULL,
  init = NULL,
  dstnodata = init
)

Value

Returns the destination filename invisibly.

Arguments

srcfile

Source raster filename.

dstfile

Output raster filename.

fmt

Output raster format name (e.g., "GTiff" or "HFA"). Will attempt to guess from the output filename if fmt is not specified.

nbands

Number of output bands.

dtName

Output raster data type name. Commonly used types include "Byte", "Int16", "UInt16", "Int32" and "Float32".

options

Optional list of format-specific creation options in a vector of "NAME=VALUE" pairs (e.g., options = c("COMPRESS=LZW") to set LZW compression during creation of a GTiff file).

init

Numeric value to initialize all pixels in the output raster.

dstnodata

Numeric nodata value for the output raster.

See Also

GDALRaster-class, create(), createCopy(), bandCopyWholeRaster(), translate()

Examples

# band 2 in a FARSITE landscape file has slope degrees
# convert slope degrees to slope percent in a new raster
lcp_file <- system.file("extdata/storm_lake.lcp", package="gdalraster")
ds_lcp <- new(GDALRaster, lcp_file)
ds_lcp$getMetadata(band=2, domain="")

slpp_file <- file.path(tempdir(), "storml_slpp.tif")
opt = c("COMPRESS=LZW")
rasterFromRaster(srcfile = lcp_file,
                 dstfile = slpp_file,
                 nbands = 1,
                 dtName = "Int16",
                 options = opt,
                 init = -32767)
ds_slp <- new(GDALRaster, slpp_file, read_only=FALSE)

# slpp_file is initialized to -32767 and nodata value set
ds_slp$getNoDataValue(band=1)

# extent and cell size are the same as lcp_file
ds_lcp$bbox()
ds_lcp$res()
ds_slp$bbox()
ds_slp$res()

# convert slope degrees in lcp_file band 2 to slope percent in slpp_file
# bring through LCP nodata -9999 to the output nodata value
ncols <- ds_slp$getRasterXSize()
nrows <- ds_slp$getRasterYSize()
for (row in 0:(nrows-1)) {
    rowdata <- ds_lcp$read(band=2,
                           xoff=0, yoff=row,
                           xsize=ncols, ysize=1,
                           out_xsize=ncols, out_ysize=1)
    rowslpp <- tan(rowdata*pi/180) * 100
    rowslpp[rowdata==-9999] <- -32767
    dim(rowslpp) <- c(1, ncols)
    ds_slp$write(band=1, xoff=0, yoff=row, xsize=ncols, ysize=1, rowslpp)
}

# min, max, mean, sd
ds_slp$getStatistics(band=1, approx_ok=FALSE, force=TRUE)

ds_slp$close()
ds_lcp$close()
deleteDataset(slpp_file)