terra (version 1.2-5)

vect: Create SpatVector objects

Description

Create a new SpatVector

Usage

# S4 method for character
vect(x, ...)
# S4 method for matrix
vect(x, type="points", atts=NULL, crs="", ...)
# S4 method for data.frame
vect(x, geom=c("lon", "lat"), crs="", ...)
# S4 method for sf
vect(x)

Arguments

x

character (filename or "Well Known Text"); or a data.frame or matrix with geometry data (see geom; or missing; or a vector object from sf or sp

type

character. Geometry type. Must be "points", "lines", or "polygons"

atts

data.frame with the attributes. The number of rows must match the number of geometrical elements

crs

the coordinate reference system (PROJ4 notation)

geom

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)

...

additional matrices and/or lists with matrices

Value

SpatVector

See Also

geom

Examples

# NOT RUN {
### from file
f <- system.file("ex/lux.shp", package="terra")
f
v <- vect(f)
v

### 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

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)
# }