read_VECT moves one GRASS vector object file with attribute data
through a temporary GeoPackage file to a terra::SpatVector
object; write_VECT moves a terra::SpatVector object
through a temporary GeoPackage file to a GRASS vector object file.
vect2neigh returns neighbour pairs with shared boundary length as
described by Markus Neteler, in
https://stat.ethz.ch/pipermail/r-sig-geo/2005-October/000616.html.
cygwin_clean_temp can be called to try to clean the GRASS
mapset-specific temporary directory under cygwin.
Usage
read_VECT(
vname,
layer = "",
proxy = FALSE,
use_gdal_grass_driver = TRUE,
type = NULL,
flags = "overwrite",
Sys_ignore.stdout = FALSE,
ignore.stderr = get.ignore.stderrOption()
)
write_VECT(
x,
vname,
flags = "overwrite",
ignore.stderr = get.ignore.stderrOption()
)
vInfo(vname, layer, ignore.stderr = NULL)
vColumns(vname, layer, ignore.stderr = NULL)
vDataCount(vname, layer, ignore.stderr = NULL)
vect2neigh(
vname,
ID = NULL,
ignore.stderr = NULL,
remove = TRUE,
vname2 = NULL,
units = "k"
)Arguments
- vname
A GRASS vector file name.
- layer
a layer name (string); if missing the first layer will be used.
- proxy
Default is
FALSE. Set asTRUEif you need aSpatVectorProxyobject.- use_gdal_grass_driver
Default
TRUE. The standalone GDAL-GRASS driver for the vector format will be used if it is installed. The advantage is that no intermediate file needs to be written from GRASS GIS and subsequently read into R; instead the vector layer is read directly from the GRASS GIS database. Please read the Note further below!.- type
override type detection when multiple types are non-zero, passed to v.out.ogr.
- flags
Character vector containing additional optional flags and/or options for v.in.ogr, particularly "o" and "overwrite".
- Sys_ignore.stdout
Passed to
system.- ignore.stderr
default the value set by
set.ignore.stderrOption; NULL, taking the value set byset.ignore.stderrOption, can be set to TRUE to silencesystem()output to standard error; does not apply on Windows platforms.- x
A
SpatVectorobject moved to GRASS.- ID
A valid DB column name for unique identifiers (optional).
- remove
default TRUE, remove copied vectors created in
vect2neigh.- vname2
If on a previous run, remove was FALSE, the name of the temporary vector may be given to circumvent its generation.
- units
default "k"; see GRASS 'v.to.db' manual page for alternatives.
Value
read_VECT imports a GRASS vector layer into a SpatVector or
SpatVectorProxy object.
vect2neigh returns a data frame object with left and right
neighbours and boundary lengths, also given class GRASSneigh and
spatial.neighbour (as used in spdep). The incantation to retrieve the
neighbours list is sn2listw(vect2neigh())$neighbours, and to
retrieve the boundary lengths: sn2listw(vect2neigh())$weights. The
GRASSneigh object has two other useful attributes: external is a vector
giving the length of shared boundary between each polygon and the external
area, and total giving each polygon's total boundary length.
Note
Be aware that the GDAL-GRASS driver may have some issues for vector data. In our experience, the error and warning messages for vector data can be ignored. Further, the returned metadata about the coordinate reference system may currently be incomplete, e.g. it may miss the EPSG code.
Author
Roger S. Bivand, e-mail: Roger.Bivand@nhh.no
Examples
# Run example if in active GRASS nc_basic_spm_grass7 location
run <- FALSE
if (nchar(Sys.getenv("GISRC")) > 0 &&
read.dcf(Sys.getenv("GISRC"))[1, "LOCATION_NAME"] == "nc_basic_spm_grass7") {
run <- TRUE
}
# Store original environment variable settings
GV <- Sys.getenv("GRASS_VERBOSE")
Sys.setenv("GRASS_VERBOSE" = 0)
ois <- get.ignore.stderrOption()
set.ignore.stderrOption(TRUE)
#> [1] FALSE
if (run) {
# Create a new mapset
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)
# Report basic metadata about the schools dataset
execGRASS("v.info", map = "schools", layer = "1")
print(vInfo("schools"))
# Read/write as a SpatVector
schs <- read_VECT("schools")
print(summary(schs))
try({
write_VECT(schs, "newsch", flags = c("o", "overwrite"))
})
schs <- read_VECT("schools", use_gdal_grass_driver = FALSE)
write_VECT(schs, "newsch", flags = c("o", "overwrite"))
execGRASS("v.info", map = "newsch", layer = "1")
nschs <- read_VECT("newsch")
print(summary(nschs))
print(all.equal(names(nschs), as.character(vColumns("newsch")[, 2])))
# Show metadata for the roadsmajor dataset and read as spatVector
print(vInfo("roadsmajor"))
roads <- read_VECT("roadsmajor")
print(summary(roads))
}
#> +----------------------------------------------------------------------------+
#> | Name: schools |
#> | Mapset: PERMANENT |
#> | Project: nc_basic_spm_grass7 |
#> | Database: /home/rsb/topics/grassdata |
#> | Title: Wake County schools (points map) |
#> | Map scale: 1:1 |
#> | Name of creator: helena |
#> | Organization: NC OneMap |
#> | Source date: Tue Nov 7 19:34:09 2006 |
#> | Timestamp (first layer): none |
#> |----------------------------------------------------------------------------|
#> | Map format: native |
#> |----------------------------------------------------------------------------|
#> | Type of map: vector (level: 2) |
#> | |
#> | Number of points: 167 Number of centroids: 0 |
#> | Number of lines: 0 Number of boundaries: 0 |
#> | Number of areas: 0 Number of islands: 0 |
#> | |
#> | Map is 3D: No |
#> | Number of dblinks: 1 |
#> | |
#> | Projection: Lambert Conformal Conic |
#> | |
#> | N: 248159.84441077 S: 203559.01136227 |
#> | E: 671714.55110786 W: 619215.13388253 |
#> | |
#> | Digitization threshold: 0 |
#> | Comment: |
#> | |
#> +----------------------------------------------------------------------------+
#>
#> nodes points lines boundaries centroids areas islands
#> 0 167 0 0 0 0 0
#> primitives map3d
#> 167 0
#> cat TAG NAMESHORT NAMELONG
#> Min. : 1.0 Length:167 Length:167 Length:167
#> 1st Qu.: 42.5 Class :character Class :character Class :character
#> Median : 84.0 Mode :character Mode :character Mode :character
#> Mean : 84.0
#> 3rd Qu.:125.5
#> Max. :167.0
#>
#> CORECAPACI MOBILEUNIT MOBILECAPA GLEVEL
#> Min. : 0.0 Min. : 0.000 Min. :0.00 Length:167
#> 1st Qu.: 498.5 1st Qu.: 0.000 1st Qu.:0.75 Class :character
#> Median : 586.0 Median : 6.000 Median :1.50 Mode :character
#> Mean : 763.7 Mean : 7.318 Mean :1.75
#> 3rd Qu.: 903.0 3rd Qu.:11.000 3rd Qu.:2.50
#> Max. :2294.0 Max. :49.000 Max. :4.00
#> NA's :23 NA's :19 NA's :163
#> LOGRADE HIGRADE CALENDAR HASBASE
#> Length:167 Length:167 Length:167 Length:167
#> Class :character Class :character Class :character Class :character
#> Mode :character Mode :character Mode :character Mode :character
#>
#>
#>
#>
#> ISMAGNET PHONE ADDRNUMBER ADDRPREFIX
#> Length:167 Length:167 Length:167 Length:167
#> Class :character Class :character Class :character Class :character
#> Mode :character Mode :character Mode :character Mode :character
#>
#>
#>
#>
#> ADDRROOT ADDRTYPE ADDRSUFFIX ADDRCITY
#> Length:167 Length:167 Length:167 Length:167
#> Class :character Class :character Class :character Class :character
#> Mode :character Mode :character Mode :character Mode :character
#>
#>
#>
#>
#> ADDRZIPCOD SPED STATUS NODEID
#> Length:167 Min. : NA Length:167 Length:167
#> Class :character 1st Qu.: NA Class :character Class :character
#> Mode :character Median : NA Mode :character Mode :character
#> Mean :NaN
#> 3rd Qu.: NA
#> Max. : NA
#> NA's :167
#> CAPACITYTO ESL BOARDDIS2 PROJ_CAP
#> Min. : 0.0 Length:167 Length:167 Min. : 0.0
#> 1st Qu.: 543.0 Class :character Class :character 1st Qu.: 497.0
#> Median : 761.0 Mode :character Mode :character Median : 722.0
#> Mean : 867.0 Mean : 793.1
#> 3rd Qu.: 992.5 3rd Qu.: 975.0
#> Max. :2294.0 Max. :2390.0
#> NA's :20 NA's :2
#> NOTES
#> Length:167
#> Class :character
#> Mode :character
#>
#>
#>
#>
#> Warning: GDAL Message 6: dataset /tmp/grass8-rsb-2581899/Rtmp054NGJ/file277d6b3b5bfa6f.gpkg does not support layer creation option ENCODING
#> Warning: GDAL Message 6: dataset /tmp/grass8-rsb-2581899/Rtmp054NGJ/file277d6b2ea1c224.gpkg does not support layer creation option ENCODING
#> +----------------------------------------------------------------------------+
#> | Name: newsch |
#> | Mapset: RGRASS_EXAMPLES |
#> | Project: nc_basic_spm_grass7 |
#> | Database: /home/rsb/topics/grassdata |
#> | Title: |
#> | Map scale: 1:1 |
#> | Name of creator: rsb |
#> | Organization: |
#> | Source date: Sat Nov 2 11:31:32 2024 |
#> | Timestamp (first layer): none |
#> |----------------------------------------------------------------------------|
#> | Map format: native |
#> |----------------------------------------------------------------------------|
#> | Type of map: vector (level: 2) |
#> | |
#> | Number of points: 167 Number of centroids: 0 |
#> | Number of lines: 0 Number of boundaries: 0 |
#> | Number of areas: 0 Number of islands: 0 |
#> | |
#> | Map is 3D: No |
#> | Number of dblinks: 1 |
#> | |
#> | Projection: Lambert Conformal Conic |
#> | |
#> | N: 248159.84441077 S: 203559.01136227 |
#> | E: 671714.55110786 W: 619215.13388253 |
#> | |
#> | Digitization threshold: 0 |
#> | Comment: |
#> | |
#> +----------------------------------------------------------------------------+
#>
#> cat cat_ TAG NAMESHORT
#> Min. : 1.0 Min. : 1.0 Length:167 Length:167
#> 1st Qu.: 42.5 1st Qu.: 42.5 Class :character Class :character
#> Median : 84.0 Median : 84.0 Mode :character Mode :character
#> Mean : 84.0 Mean : 84.0
#> 3rd Qu.:125.5 3rd Qu.:125.5
#> Max. :167.0 Max. :167.0
#>
#> NAMELONG CORECAPACI MOBILEUNIT MOBILECAPA
#> Length:167 Min. : 0.0 Min. : 0.000 Min. :0.00
#> Class :character 1st Qu.: 498.5 1st Qu.: 0.000 1st Qu.:0.75
#> Mode :character Median : 586.0 Median : 6.000 Median :1.50
#> Mean : 763.7 Mean : 7.318 Mean :1.75
#> 3rd Qu.: 903.0 3rd Qu.:11.000 3rd Qu.:2.50
#> Max. :2294.0 Max. :49.000 Max. :4.00
#> NA's :23 NA's :19 NA's :163
#> GLEVEL LOGRADE HIGRADE CALENDAR
#> Length:167 Length:167 Length:167 Length:167
#> Class :character Class :character Class :character Class :character
#> Mode :character Mode :character Mode :character Mode :character
#>
#>
#>
#>
#> HASBASE ISMAGNET PHONE ADDRNUMBER
#> Length:167 Length:167 Length:167 Length:167
#> Class :character Class :character Class :character Class :character
#> Mode :character Mode :character Mode :character Mode :character
#>
#>
#>
#>
#> ADDRPREFIX ADDRROOT ADDRTYPE ADDRSUFFIX
#> Length:167 Length:167 Length:167 Length:167
#> Class :character Class :character Class :character Class :character
#> Mode :character Mode :character Mode :character Mode :character
#>
#>
#>
#>
#> ADDRCITY ADDRZIPCOD SPED STATUS
#> Length:167 Length:167 Min. : NA Length:167
#> Class :character Class :character 1st Qu.: NA Class :character
#> Mode :character Mode :character Median : NA Mode :character
#> Mean :NaN
#> 3rd Qu.: NA
#> Max. : NA
#> NA's :167
#> NODEID CAPACITYTO ESL BOARDDIS2
#> Length:167 Min. : 0.0 Length:167 Length:167
#> Class :character 1st Qu.: 543.0 Class :character Class :character
#> Mode :character Median : 761.0 Mode :character Mode :character
#> Mean : 867.0
#> 3rd Qu.: 992.5
#> Max. :2294.0
#> NA's :20
#> PROJ_CAP NOTES
#> Min. : 0.0 Length:167
#> 1st Qu.: 497.0 Class :character
#> Median : 722.0 Mode :character
#> Mean : 793.1
#> 3rd Qu.: 975.0
#> Max. :2390.0
#> NA's :2
#> [1] TRUE
#> nodes points lines boundaries centroids areas islands
#> 266 0 355 0 0 0 0
#> primitives map3d
#> 355 0
#> cat MAJORRDS_ ROAD_NAME MULTILANE
#> Min. : 1.0 Min. : 1.0 Length:355 Length:355
#> 1st Qu.: 89.5 1st Qu.: 91.5 Class :character Class :character
#> Median :178.0 Median :180.0 Mode :character Mode :character
#> Mean :178.0 Mean :179.8
#> 3rd Qu.:266.5 3rd Qu.:268.5
#> Max. :355.0 Max. :357.0
#> PROPYEAR OBJECTID SHAPE_LEN
#> Min. : 0.0 Min. : 1.0 Min. : 20.36
#> 1st Qu.: 0.0 1st Qu.: 89.5 1st Qu.: 763.32
#> Median : 0.0 Median :178.0 Median : 1601.23
#> Mean : 192.7 Mean :178.0 Mean : 4934.15
#> 3rd Qu.: 0.0 3rd Qu.:266.5 3rd Qu.: 9555.59
#> Max. :2025.0 Max. :355.0 Max. :64177.26
# not run: vect2neigh() currently writes 3 new data sources in the PERMANENT
# mapset, despite this mapset not being the active one.
if (FALSE) {
cen_neig <- vect2neigh("census")
str(cen_neig)
}
# Cleanup the previously created datasets
if (run) {
execGRASS(
"g.remove",
flags = "f",
name = c("newsch", "newsch1"),
type = "vector"
)
execGRASS("g.mapset", mapset = previous_mapset)
if (example_mapset != previous_mapset) {
unlink(file.path(location_path, example_mapset), recursive = TRUE)
}
}
# Restore environment variable settings
Sys.setenv("GRASS_VERBOSE" = GV)
set.ignore.stderrOption(ois)
#> [1] TRUE