Split polygons or lines to segments

Source: R/st_segments.R

Split lines or polygons to separate segments.

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)))
#> Warning: st_centroid assumes attributes are constant over geometries


par(opar)