readRAST {rgrass}

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, ignore.stderr=get.ignore.stderrOption(),
 return_format="terra", close_OK=return_format=="SGDF", flags=NULL)
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"

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) {
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$elevation)
}
if (run) {
  write_RAST(nc_basic, "sqdemSP", zcol="sqdem", flags=c("quiet", "overwrite"))
  execGRASS("r.info", map="sqdemSP")
}
if (run) {
  print(system.time(sqdemSP <- read_RAST(c("sqdemSP", "elevation"),
    return_format="SGDF")))
}
if (run) {
  print(system.time(sqdem <- read_RAST(c("sqdemSP", "elevation"),
    return_format="terra")))
}
if (run) {
names(sqdem)
}
if (run) {
  try(sqdem1 <- read_RAST(c("sqdemSP@rsb", "elevation@PERMANENT")))
}
if (run) {
names(sqdem1)
}
if (run) {
  execGRASS("g.remove", flags="f", name="sqdemSP", type="raster")
  execGRASS("r.mapcalc", expression="basins0 = basins - 1", flags="overwrite")
  execGRASS("r.stats", flags="c", input="basins0")
}
if (run) {
  basins0 <- read_RAST("basins0", return_format="SGDF")
  print(table(basins0$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")
}
Sys.setenv("GRASS_VERBOSE"=GV)
set.ignore.stderrOption(ois)