geos (version 0.2.5)

geos_intersection: Binary geometry operators

Description

• geos_intersection() returns the set of points common to both x and y.

• geos_difference() returns the set of points from x that are not contained by y.

• geos_sym_difference() returns the set of points that are not common to x and y.

• geos_union() returns the set of points contained by either x or y.

• geos_shared_paths() returns a GEOMETRYCOLLECTION containing two MULTILINESTRINGS: the first containing paths in the same direction, the second containing common paths in the opposite direction.

• geos_snap() snaps the vertices of x within tolerance of y to y.

• geos_clearance_line_between() calculate the clearance (shortest distance) between x and y, result is a LINESTRING that touches each geometry.

Usage

geos_intersection(geom1, geom2)
geos_difference(geom1, geom2)
geos_sym_difference(geom1, geom2)
geos_union(geom1, geom2)
geos_intersection_prec(geom1, geom2, grid_size)
geos_difference_prec(geom1, geom2, grid_size)
geos_sym_difference_prec(geom1, geom2, grid_size)
geos_union_prec(geom1, geom2, grid_size)
geos_shared_paths(geom1, geom2)
geos_snap(geom1, geom2, tolerance = .Machine$double.eps^2)
geos_clearance_line_between(geom1, geom2, prepare = FALSE)

Value

A GEOS geometry vector along the recycled length of geom1 and geom2.

Arguments

geom1, geom2

GEOS geometry vectors, recycled to a common length.

grid_size

For _prec() variants, the grid size such that all vertices of the resulting geometry will lie on the grid.

tolerance

The maximum separation of vertices that should be considered equal.

prepare

Use prepared geometries to calculate clearance line

Examples

poly1 <- "POLYGON ((0 0, 0 10, 10 10, 10 0, 0 0))"
poly2 <- "POLYGON ((5 5, 5 15, 15 15, 15 5, 5 5))"

geos_intersection(poly1, poly2)
geos_difference(poly1, poly2)
geos_sym_difference(poly1, poly2)
geos_union(poly1, poly2)

line <- "LINESTRING (11 0, 11 10)"
geos_snap(poly1, line, tolerance = 2)

geos_shared_paths("LINESTRING (0 0, 1 1, 2 2)", "LINESTRING (3 3, 2 2, 1 1)")

## generate a line that connects two geometries at their nearest place
## (not necessarily a vertex of either)
a <- as_geos_geometry("LINESTRING (0.5 2, 0.5 3)")
b <- as_geos_geometry("POLYGON ((0 1, 0.5 0, 1 1, 0 1))")
plot(c(a, b), col = c("grey", "firebrick"), lwd = 10)
plot(geos_clearance_line_between(a, b), add = TRUE)