st_segments: Split polygons or lines to segments

In michaeldorman/nngeo: k-Nearest Neighbor Join for Spatial Data

Split polygons or lines to segments

Description

Split lines or polygons to separate segments.

Usage

st_segments(x, progress = TRUE)

Arguments

x	An object of class sfg, sfc or sf, with geometry type LINESTRING, MULTILINESTRING, POLYGON or MULTIPOLYGON
progress	Display progress bar? (default TRUE)

Value

An sf layer of type LINESTRING where each segment is represented by a separate feature

Examples

# Sample geometries
s1 = rbind(c(0,3),c(0,4),c(1,5),c(2,5))
ls = st_linestring(s1)
s2 = rbind(c(0.2,3), c(0.2,4), c(1,4.8), c(2,4.8))
s3 = rbind(c(0,4.4), c(0.6,5))
mls = st_multilinestring(list(s1,s2,s3))
p1 = rbind(c(0,0), c(1,0), c(3,2), c(2,4), c(1,4), c(0,0))
p2 = rbind(c(1,1), c(1,2), c(2,2), c(1,1))
pol = st_polygon(list(p1,p2))
p3 = rbind(c(3,0), c(4,0), c(4,1), c(3,1), c(3,0))
p4 = rbind(c(3.3,0.3), c(3.8,0.3), c(3.8,0.8), c(3.3,0.8), c(3.3,0.3))[5:1,]
p5 = rbind(c(3,3), c(4,2), c(4,3), c(3,3))
mpol = st_multipolygon(list(list(p1,p2), list(p3,p4), list(p5)))

# Geometries ('sfg')
opar = par(mfrow = c(1, 2))

plot(ls)
seg = st_segments(ls, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

plot(mls)
seg = st_segments(mls, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

plot(pol)
seg = st_segments(pol, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

plot(mpol)
seg = st_segments(mpol, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

par(opar)

# Columns ('sfc')
opar = par(mfrow = c(1, 2))

ls = st_sfc(ls)
plot(ls)
seg = st_segments(ls, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

ls2 = st_sfc(c(ls, ls + c(1, -1), ls + c(-3, -1)))
plot(ls2)
seg = st_segments(ls2, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

mls = st_sfc(mls)
plot(mls)
seg = st_segments(mls, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

mls2 = st_sfc(c(mls, mls + c(1, -2)))
plot(mls2)
seg = st_segments(mls2, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

pol = st_sfc(pol)
plot(pol)
seg = st_segments(pol, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

mpol = st_sfc(mpol)
plot(mpol)
seg = st_segments(mpol, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

mpol2 = st_sfc(c(mpol, mpol + c(5, 2)))
plot(mpol2)
seg = st_segments(mpol2, progress = FALSE)
plot(seg, col = rainbow(length(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:length(seg)))

par(opar)

# Layers ('sf')
opar = par(mfrow = c(1, 2))

mpol_sf = st_sf(id = 1:2, type = c("a", "b"), geom = st_sfc(c(mpol, mpol + c(5, 2))))
plot(st_geometry(mpol_sf))
seg = st_segments(mpol_sf, progress = FALSE)
plot(st_geometry(seg), col = rainbow(nrow(seg)))
text(st_coordinates(st_centroid(seg)), as.character(1:nrow(seg)))

par(opar)

michaeldorman/nngeo documentation built on April 19, 2024, 12:04 a.m.