st_nearest_points: get nearest points between pairs of geometries

In sf: Simple Features for R

get nearest points between pairs of geometries

Description

get nearest points between pairs of geometries

Usage

st_nearest_points(x, y, ...)

## S3 method for class 'sfc'
st_nearest_points(x, y, ..., pairwise = FALSE)

## S3 method for class 'sfg'
st_nearest_points(x, y, ...)

## S3 method for class 'sf'
st_nearest_points(x, y, ...)

Arguments

x	object of class sfg, sfc or sf
y	object of class sfg, sfc or sf
...	ignored
pairwise	logical; if FALSE (default) return nearest points between all pairs, if TRUE, return nearest points between subsequent pairs.

Details

in case x lies inside y, when using S2, the end points are on polygon boundaries, when using GEOS the end point are identical to x.

Value

an sfc object with all two-point LINESTRING geometries of point pairs from the first to the second geometry, of length x * y, with y cycling fastest. See examples for ideas how to convert these to POINT geometries.

See Also

st_nearest_feature for finding the nearest feature

Examples

r = sqrt(2)/10
pt1 = st_point(c(.1,.1))
pt2 = st_point(c(.9,.9))
pt3 = st_point(c(.9,.1))
b1 = st_buffer(pt1, r)
b2 = st_buffer(pt2, r)
b3 = st_buffer(pt3, r)
(ls0 = st_nearest_points(b1, b2)) # sfg
(ls = st_nearest_points(st_sfc(b1), st_sfc(b2, b3))) # sfc
plot(b1, xlim = c(-.2,1.2), ylim = c(-.2,1.2), col = NA, border = 'green')
plot(st_sfc(b2, b3), add = TRUE, col = NA, border = 'blue')
plot(ls, add = TRUE, col = 'red')

nc = st_read(system.file("gpkg/nc.gpkg", package="sf"))
plot(st_geometry(nc))
ls = st_nearest_points(nc[1,], nc)
plot(ls, col = 'red', add = TRUE)
pts = st_cast(ls, "POINT") # gives all start & end points
# starting, "from" points, corresponding to x:
plot(pts[seq(1, 200, 2)], add = TRUE, col = 'blue')
# ending, "to" points, corresponding to y:
plot(pts[seq(2, 200, 2)], add = TRUE, col = 'green')

sf documentation built on Oct. 11, 2024, 9:08 a.m.