readRAST: Read and write GRASS raster files

In rgrass: Interface Between 'GRASS' Geographical Information System and 'R'

Read and write GRASS raster files

Description

Read GRASS raster files from GRASS into R terra "SpatRaster" or sp "SpatialGridDataFrame" objects, and write single columns of terra "SpatRaster" or sp "SpatialGridDataFrame" objects to GRASS. When return_format="terra", temporary binary files and r.out.bin and r.in.bin are used for speed reasons. read_RAST() and write_RAST() by default use "RRASTER" files written and read by GDAL.

Usage

read_RAST(vname, cat=NULL, NODATA=NULL,
 return_format="terra", close_OK=return_format=="SGDF",
 flags=NULL, Sys_ignore.stdout = FALSE, ignore.stderr=get.ignore.stderrOption())
write_RAST(x, vname, zcol = 1, NODATA=NULL, flags=NULL,
 ignore.stderr = get.ignore.stderrOption(), overwrite=FALSE, verbose=TRUE)

Arguments

vname	A vector of GRASS raster file names in mapsets in the current search path, as set by “g.mapsets”; the file names may be given as fully-qualified map names using “name@mapset”, in which case only the mapset given in the full path will be searched for the existence of the raster; if more than one raster with the same name is found in mapsets in the current search path, an error will occur, in which case the user should give the fully-qualified map name. If the fully-qualified name is used, @ will be replaced by underscore in the output object.
cat	default NULL; if not NULL, must be a logical vector matching vname, stating which (CELL) rasters to return as factor
return_format	default "terra", optionally "SGDF"
Sys_ignore.stdout	Passed to system.
ignore.stderr	default taking the value set by set.ignore.stderrOption; can be set to TRUE to silence system() output to standard error; does not apply on Windows platforms
close_OK	default TRUE - clean up possible open connections used for reading metadata; may be set to FALSE to avoid the side-effect of other user-opened connections being broken
x	A terra "SpatRaster" or sp "SpatialGridDataFrame" object
zcol	Attribute column number or name
NODATA	by default NULL, in which case it is set to one less than floor() of the data values for FCELL rasters or the range maximum for CELL Byte, UInt16 and Uint32 rasters (with no negative values), and an attempt is made to set NODATA to the upper Int16 and Int32 range if the lower range is occupied; otherwise an integer NODATA value (required to be integer by GRASS r.out.bin)
overwrite	default FALSE, if TRUE inserts "overwrite" into the value of the flags argument if not already there to allow existing GRASS rasters to be overwritten
flags	default NULL, character vector, for example "overwrite"
verbose	default TRUE, report how writing to GRASS is specified

Value

read_RAST by default returns a SpatRaster object, but may return a legacy SpatialGridDataFrame object if return_format="SGDF". write_RAST silently returns the object being written to GRASS.

Author(s)

Roger S. Bivand, e-mail: [e-mail]

Examples

run <- FALSE
if (nchar(Sys.getenv("GISRC")) > 0 &&
    read.dcf(Sys.getenv("GISRC"))[1,"LOCATION_NAME"] == "nc_basic_spm_grass7") run <- TRUE
GV <- Sys.getenv("GRASS_VERBOSE")
Sys.setenv("GRASS_VERBOSE"=0)
ois <- get.ignore.stderrOption()
set.ignore.stderrOption(TRUE)
if (run) {
  meta <- gmeta()
  location_path <- file.path(meta$GISDBASE, meta$LOCATION_NAME)
  previous_mapset <- meta$MAPSET
  example_mapset <- "RGRASS_EXAMPLES"
  execGRASS("g.mapset", "c", mapset = example_mapset)
}

if (run) {
  unlist(strsplit(execGRASS("g.mapsets", flags="p", intern=TRUE), " "))
}
if (run) {
  execGRASS("g.list", type="raster", pattern="soils", flags="m", intern=TRUE)
}
if (run) {
  execGRASS("g.list", type="raster", pattern="soils@PERMANENT", mapset=".", flags="m", intern=TRUE)
}
if (run) {
  execGRASS("g.list", type="raster", pattern="soils", mapset="PERMANENT", flags="m", intern=TRUE)
}
run <- run && require("terra", quietly=TRUE)
if (run) {
  v1 <- read_RAST("landuse", cat=TRUE, return_format="terra")
  v1
  inMemory(v1)
}
if (run) {
  write_RAST(v1, "landuse1", flags=c("o", "overwrite"))
  execGRASS("r.stats", flags="c", input="landuse1")
  execGRASS("g.remove", flags="f", name="landuse1", type="raster")
}
Sys.setenv("_SP_EVOLUTION_STATUS_"="2")
run <- run && require("sp", quietly=TRUE)
if (run) {
  nc_basic <- read_RAST(c("geology", "elevation"), cat=c(TRUE, FALSE),
                        return_format="SGDF")
  print(table(nc_basic$geology))
}
if (run) {
  execGRASS("r.stats", flags=c("c", "l", "quiet"), input="geology")
}
if (run) {
  boxplot(nc_basic$elevation ~ nc_basic$geology)
}
if (run) {
  nc_basic$sqdem <- sqrt(nc_basic$elevation)
}
if (run) {
  write_RAST(nc_basic, "sqdemSP", zcol="sqdem", flags=c("quiet", "overwrite"))
  execGRASS("r.info", map="sqdemSP")
}
if (run) {
  print(system.time(sqdemSP <- read_RAST(c("sqdemSP", "elevation"),
                                         return_format="SGDF")))
}
if (run) {
  print(system.time(sqdem <- read_RAST(c("sqdemSP", "elevation"),
    return_format="terra")))
}
if (run) {
names(sqdem)
}
if (run) {
  sqdem1 <- read_RAST(c("sqdemSP@RGRASS_EXAMPLES", "elevation@PERMANENT"))
}
if (run) {
  names(sqdem1)
}
if (run) {
  execGRASS("g.remove", flags="f", name="sqdemSP", type="raster")
  execGRASS("r.mapcalc", expression="basins0 = basins - 1", flags="overwrite")
  execGRASS("r.stats", flags="c", input="basins0")
}
if (run) {
  basins0 <- read_RAST("basins0", return_format="SGDF")
  print(table(basins0$basins0))
}
if (run) {
  execGRASS("g.remove", flags="f", name="basins0", type="raster")
}
if (run) {
  execGRASS(cmd = "r.mapcalc", expression="test_t=66000", flags="overwrite")
  execGRASS("r.info", flags = "r", map = "test_t", intern = TRUE) # #82
}
if (run) {
  (tt = read_RAST(vname = "test_t"))
}
if (run) {
  execGRASS("g.remove", flags="f", name="test_t", type="raster")
}
if (run) {
  execGRASS("g.mapset", mapset = previous_mapset)
  if (example_mapset != previous_mapset) {
    unlink(file.path(location_path, example_mapset), recursive = TRUE)
  }
}
Sys.setenv("GRASS_VERBOSE"=GV)
set.ignore.stderrOption(ois)

rgrass documentation built on Sept. 11, 2024, 7:55 p.m.