Create a raster from an existing raster as template

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
)

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.

Value

Returns the destination filename invisibly.

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 = "")
#> [1] "SLOPE_FILE=/netapp/sharedwebfs1/shared/landfire/public/temp_q8dTbIJ4w6Qi36Omkzk0/LCP_LF2022_FBFM40_220_CONUS/temp/merged_modified.tif"
#> [2] "SLOPE_MAX=54"                                                                                                                         
#> [3] "SLOPE_MIN=-9999"                                                                                                                      
#> [4] "SLOPE_NUM_CLASSES=53"                                                                                                                 
#> [5] "SLOPE_UNIT=0"                                                                                                                         
#> [6] "SLOPE_UNIT_NAME=Degrees"                                                                                                              

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)
#> initializing destination raster...
#> done
ds_slp <- new(GDALRaster, slpp_file, read_only = FALSE)

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

# extent and cell size are the same as lcp_file
ds_lcp$bbox()
#> [1]  323476.1 5101872.0  327766.1 5105082.0
ds_lcp$res()
#> [1] 30 30
ds_slp$bbox()
#> [1]  323476.1 5101872.0  327766.1 5105082.0
ds_slp$res()
#> [1] 30 30

# 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,
                 rasterData = rowslpp)
}

# min, max, mean, sd
ds_slp$getStatistics(band = 1, approx_ok = FALSE, force = TRUE)
#> 0...10...20...30...40...50...60...70...80...90...100 - done.
#> [1]   0.00000 138.00000  44.76464  26.79985

ds_slp$close()
ds_lcp$close()

Usage

Arguments

Value

See also

Examples