Last chance! 50% off unlimited learning
Sale ends in
Query a SpatVectorProxy to extract a subset
# S4 method for SpatVectorProxy
query(x, start=1, n=nrow(x), vars=NULL, where=NULL,
extent=NULL, filter=NULL, sql=NULL, what="")
SpatVector
SpatVectorProxy
positive integer. The record to start reading at
positive integer. The number of records requested
character. Variable names. Must be a subset of names(x)
character. expression like "NAME_1='California' AND ID > 3" , to subset records. Note that start and n are applied after executing the where statement
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)
character. Arbitrary SQL statement. If used, arguments "start", "n", "vars" and "where" are ignored
character indicating what to read. Either ""
for geometries and attributes, or "geoms"
to only read the geometries, "attributes"
to only read the attributes (that are returned as a data.frame)
vect
f <- system.file("ex/lux.shp", package="terra")
v <- vect(f, proxy=TRUE)
v
x <- query(v, vars=c("ID_2", "NAME_2"), start=5, n=2)
x
query(v, vars=c("ID_2", "NAME_1", "NAME_2"), where="NAME_1='Grevenmacher' AND ID_2 > 6")
## with an extent
e <- ext(5.9, 6.3, 49.9, 50)
x <- query(v, extent=e)
## with polygons
p <- as.polygons(e)
x <- query(v, filter=p)
x
Run the code above in your browser using DataLab