link2GI (version 0.5-3)

linkGRASS7: Deprecated only for backwards compatibility Locate and set up 'GRASS' API bindings

Description

Initializes the session environment and the system paths for an easy access to 'GRASS GIS 7.x/8.x'. The correct setup of the spatial and projection parameters is automatically performed by using either an existing and valid raster, terra, sp or sf object, or manually by providing a list containing the minimum parameters needed.

Usage

linkGRASS7(
  x = NULL,
  default_GRASS = NULL,
  search_path = NULL,
  ver_select = FALSE,
  gisdbase_exist = FALSE,
  gisdbase = NULL,
  use_home = FALSE,
  location = NULL,
  spatial_params = NULL,
  resolution = NULL,
  quiet = TRUE,
  returnPaths = TRUE
)

Arguments

x

raster/terra or sp/sf object

default_GRASS

default is NULL If is NULL an automatic search for all installed versions is performed. If you provide a valid list the corresponding version is initialized. An example for OSGeo4W64 is: c("C:/OSGeo4W64","grass-7.0.5","osgeo4w")

search_path

path or mounting point that will be searched

ver_select

boolean if TRUE you may choose interactively the binary version (if found more than one), by default FALSE

gisdbase_exist

default is FALSE if set to TRUE the arguments gisdbase and location are expected to be an existing GRASS gisdbase

gisdbase

default is NULL, invoke tempdir() to the 'GRASS' database. Alternativeley you can provide a individual path.

use_home

default is FALSE, set the GISRC path to tempdir(), if TRUE the HOME or USERPROFILE setting is used for writing the GISRC file

location

default is NULL, invoke basename(tempfile()) for defining the 'GRASS' location. Alternativeley you can provide a individual path.

spatial_params

default is NULL. Instead of a spatial object you may provide the geometry as a list. E.g. c(xmin,ymin,xmax,ymax,proj4_string)

resolution

resolution in map units for the GRASS raster cells

quiet

boolean switch for supressing console messages default is TRUE

returnPaths

boolean if set to FALSE the pathes of the selected version are written to the PATH variable only, otherwise all paths and versions of the installed GRASS versions ae returned.

Author

Chris Reudenbach

Details

The concept is straightforward but for an all days usage helpful. Either you need to provide a raster or sp sf spatial object which has correct spatial and projection properties or you may link directlxy to an existing 'GRASS' gisdbase and mapset. If you choose an spatial object to initialize a correct 'GRASS' mapset it is used to create either a temporary or a permanent rgrass environment including the correct 'GRASS ' structure.

The most time consuming part on 'Windows' Systems is the search process. This can easily take 10 or more minutes. To speed up this process you can also provide a correct parameter set. Best way to do so is to call searchGRASSW or for 'Linux' searchGRASSX manually. and call linkGRASS with the version arguments of your choice. linkGRASS initializes the usage of GRASS.

Examples

if (FALSE) {
library(link2GI)
require(sf)

# proj folders
projRootDir = tempdir()
paths = link2GI::initProj(projRootDir = projRootDir,
                         projFolders = c("project1/"))
                         
# get  data                         
nc = st_read(system.file("shape/nc.shp", package="sf"))

# Automatic search and find of GRASS binaries 
# using the nc sf data object for spatial referencing
# This is the highly recommended linking procedure for on the fly jobs
# NOTE: if more than one GRASS installation is found you have to choose. 
grass = linkGRASS(nc,returnPaths = TRUE)
if (grass$exist){

# CREATE and link to a permanent GRASS folder at "projRootDir", location named "project1" 
linkGRASS(nc, gisdbase = projRootDir, location = "project1")   

# ONLY LINK to a permanent GRASS folder at "projRootDir", location named "project1" 
linkGRASS(gisdbase = projRootDir, location = "project1", gisdbase_exist = TRUE )   


# setting up GRASS manually with spatial parameters of the nc data
proj4_string = as.character(sp::CRS("+init=epsg:28992"))
linkGRASS(spatial_params = c(178605,329714,181390,333611,proj4_string)) 

# creating a GRASS gisdbase manually with spatial parameters of the nc data 
# additionally using a peramanent directory "projRootDir" and the location "nc_spatial_params "
proj4_string = as.character(sp::CRS("+init=epsg:4267"))
linkGRASS(gisdbase = projRootDir,
           location = "nc_spatial_params",
           spatial_params = c(-84.32385, 33.88199,-75.45698,36.58965,proj4_string))
}

## Some more examples related to interactive selection or OS specific settings

# SELECT the GRASS installation and define the search location
linkGRASS(nc, ver_select = TRUE, search_path = "~")

# SELECT the GRASS installation 
linkGRASS(nc, ver_select = TRUE)

# Typical osge4W installation (QGIS), using the meuse sp data object for spatial referencing
linkGRASS(nc,c("C:/Program Files/QGIS 2.18","grass-7.2.1","osgeo4W")) 

# Typical osgeo4W installation (rootdir), using the meuse sp data object for spatial referencing 
linkGRASS(nc,c("C:/OSGeo4W64/","grass-7.2.2","osgeo4W"))

}