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Geometric operations on pairs of simple feature geometry sets (including sftime objects)

Source: R/geom-transformers.R
geos_binary_ops.Rd

Geometric operations on pairs of simple feature geometry sets (including sftime objects)

Intersection

Difference

Usage

# S3 method for class 'sftime'
st_intersection(x, y, ...)

# S3 method for class 'sftime'
st_difference(x, y, ...)

# S3 method for class 'sftime'
st_sym_difference(x, y, ...)

Arguments

x

object of class sftime, sf, sfc or sfg.

y

object of class sftime, sf, sfc or sfg.

...

See geos_binary_ops.

Value

The intersection, difference or symmetric difference between two sets of geometries. The returned object has the same class as that of the first argument (x) with the non-empty geometries resulting from applying the operation to all geometry pairs in x and y. In case x is of class sf or sftime, the matching attributes of the original object(s) are added. The sfc geometry list-column returned carries an attribute idx, which is an n-by-2 matrix with every row the index of the corresponding entries of x and y, respectively.

Details

st_intersection: When called with a missing y, the sftime method for st_intersection returns an sftime object with attributes taken from the contributing feature with lowest index; two fields are added:

n.overlaps

The number of overlapping features in x.

origins

A list-column with indexes of all overlapping features.

st_difference: When st_difference is called with a single argument, overlapping areas are erased from geometries that are indexed at greater numbers in the argument to x; geometries that are empty or contained fully inside geometries with higher priority are removed entirely.

Examples

g <- st_sfc(st_point(c(1, 2)), st_point(c(1, 3)), st_point(c(2, 3)), 
     st_point(c(2, 1)), st_point(c(3, 1)))
tc <- Sys.time() + 1:5
x1 <- st_sftime(a = 1:5, g, time = tc)
x2 <- st_buffer(x1, dist = 1)

## intersection

# only x provided (no y)
plot(st_intersection(x2))
#> [INFO] Fewer time stamps in the data than asked for; argument 'number' set to: 5

#> NULL

# with arguments x and y provided
plot(st_intersection(x2, x1))
#> Warning: attribute variables are assumed to be spatially constant throughout all geometries
#> [INFO] Fewer time stamps in the data than asked for; argument 'number' set to: 5

#> NULL

## difference

# only x provided (no y)
plot(st_difference(x2))
#> [INFO] Fewer time stamps in the data than asked for; argument 'number' set to: 5

#> NULL

# with arguments x and y provided
plot(st_difference(x2, x1))
#> Warning: attribute variables are assumed to be spatially constant throughout all geometries
#> [INFO] Fewer time stamps in the data than asked for; argument 'number' set to: 5

#> NULL

## symmetric difference
plot(st_sym_difference(x1, x2))
#> Warning: attribute variables are assumed to be spatially constant throughout all geometries
#> [INFO] Fewer time stamps in the data than asked for; argument 'number' set to: 5

#> NULL