vect.Rd
Methods to create a SpatVector from a filename or other R object.
A filename can be for a shapefile or any spatial file format.
You can use a data.frame to make a SpatVector of points; or a "geom" matrix to make a SpatVector of any supported geometry (see examples and geom
).
You can supply a list of SpatVectors to append them into a single SpatVector.
SpatVectors can also be created from "Well Known Text", and from spatial vector data objects defined in the sf
or sp
packages.
# S4 method for character
vect(x, layer="", query="", extent=NULL, filter=NULL,
crs="", proxy=FALSE, what="")
# S4 method for matrix
vect(x, type="points", atts=NULL, crs="")
# S4 method for data.frame
vect(x, geom=c("lon", "lat"), crs="", keepgeom=FALSE)
# S4 method for list
vect(x, type="points", crs="")
# S4 method for SpatExtent
vect(x, crs="")
# S4 method for sf
vect(x)
character. A filename; or a "Well Known Text" string; SpatExtent, data.frame (to make a SpatVector of points); a "geom" matrix to make a SpatVector of any supported geometry (see examples and geom
); a spatial vector data object defined in the sf
or sp
packages; or a list with matrices with coordinates
character. layer name to select a layer from a file (database) with multiple layers
character. An query to subset the dataset in the OGR-SQL dialect
Spat* object. The extent of the object is used as a spatial filter to select the geometries to read. Ignored if filter
is not NULL
SpatVector. Used as a spatial filter to select geometries to read (the convex hull is used for lines or points). It is guaranteed that all features that overlap with the extent of filter will be returned. It can happen that additional geometries are returned
character. Geometry type. Must be "points", "lines", or "polygons"
data.frame with the attributes. The number of rows must match the number of geometrical elements
character. The coordinate reference system in one of the following formats: WKT/WKT2, <authority>:<code>, or PROJ-string notation (see crs
). See crs
logical. If TRUE
a SpatVectorProxy is returned
character indicating what to read. Either ""
for geometries and attributes, geoms
to only read the geometries, attributes
to only read the attributes (that are returned as a data.frame)
character. The field name(s) with the geometry data. Either two names for x and y coordinates of points, or a single name for a single column with WKT geometries)
logical. If TRUE
the geom variable(s) is (are) also included in the attributes
SpatVector
### SpatVector from file
f <- system.file("ex/lux.shp", package="terra")
f
#> [1] "/Users/runner/work/_temp/Library/terra/ex/lux.shp"
v <- vect(f)
v
#> class : SpatVector
#> geometry : polygons
#> dimensions : 12, 6 (geometries, attributes)
#> extent : 5.74414, 6.528252, 49.44781, 50.18162 (xmin, xmax, ymin, ymax)
#> source : lux.shp
#> coord. ref. : lon/lat WGS 84 (EPSG:4326)
#> names : ID_1 NAME_1 ID_2 NAME_2 AREA POP
#> type : <num> <chr> <num> <chr> <num> <int>
#> values : 1 Diekirch 1 Clervaux 312 18081
#> 1 Diekirch 2 Diekirch 218 32543
#> 1 Diekirch 3 Redange 259 18664
## subsetting (large) files
## with attribute query
v <- vect(f, query="SELECT NAME_1, NAME_2, ID_2 FROM lux WHERE ID_2 < 4")
v
#> class : SpatVector
#> geometry : polygons
#> dimensions : 3, 3 (geometries, attributes)
#> extent : 5.746118, 6.315773, 49.69933, 50.18162 (xmin, xmax, ymin, ymax)
#> source : lux.shp
#> coord. ref. : lon/lat WGS 84 (EPSG:4326)
#> names : NAME_1 NAME_2 ID_2
#> type : <chr> <chr> <num>
#> values : Diekirch Clervaux 1
#> Diekirch Diekirch 2
#> Diekirch Redange 3
## with an extent
e <- ext(5.9, 6.3, 49.9, 50)
v <- vect(f, extent=e)
## with polygons
p <- as.polygons(e)
v <- vect(f, filter=p)
### SpatVector from a geom matrix
x1 <- rbind(c(-180,-20), c(-140,55), c(10, 0), c(-140,-60))
x2 <- rbind(c(-10,0), c(140,60), c(160,0), c(140,-55))
x3 <- rbind(c(-125,0), c(0,60), c(40,5), c(15,-45))
hole <- rbind(c(80,0), c(105,13), c(120,2), c(105,-13))
z <- rbind(cbind(object=1, part=1, x1, hole=0), cbind(object=2, part=1, x3, hole=0),
cbind(object=3, part=1, x2, hole=0), cbind(object=3, part=1, hole, hole=1))
colnames(z)[3:4] <- c('x', 'y')
p <- vect(z, "polygons")
p
#> class : SpatVector
#> geometry : polygons
#> dimensions : 3, 0 (geometries, attributes)
#> extent : -180, 160, -60, 60 (xmin, xmax, ymin, ymax)
#> coord. ref. :
z[z[, "hole"]==1, "object"] <- 4
lns <- vect(z[,1:4], "lines")
plot(p)
lines(lns, col="red", lwd=2)
### from wkt
v <- vect("POLYGON ((0 -5, 10 0, 10 -10, 0 -5))")
wkt <- c("MULTIPOLYGON ( ((40 40, 20 45, 45 30, 40 40)),
((20 35, 10 30, 10 10, 30 5, 45 20, 20 35),(30 20, 20 15, 20 25, 30 20)))",
"POLYGON ((0 -5, 10 0, 10 -10, 0 -5))")
w <- vect(wkt)
# combine two SpatVectors
vw <- rbind(w, v)
# add a data.frame
d <- data.frame(id=1:2, name=c("a", "b"))
values(w) <- d
# add data.frame on creation, here from a geom matrix
g <- geom(w)
d <- data.frame(id=1:2, name=c("a", "b"))
m <- vect(g, "polygons", atts=d, crs="+proj=longlat +datum=WGS84")
### SpatVector from a data.frame
d$wkt <- wkt
x <- vect(d, geom="wkt")
d$wkt <- NULL
d$lon <- c(0,10)
d$lat <- c(0,10)
x <- vect(d, geom=c("lon", "lat"))
# SpatVector to sf
#sf::st_as_sf(x)