st_line_project_point: Project point on linestring, interpolate along a linestring

In sf: Simple Features for R

Project point on linestring, interpolate along a linestring

Description

Project point on linestring, interpolate along a linestring

Usage

st_line_project(line, point, normalized = FALSE)

st_line_interpolate(line, dist, normalized = FALSE)

Arguments

line	object of class sfc with LINESTRING geometry
point	object of class sfc with POINT geometry
normalized	logical; if TRUE, use or return distance normalised to 0-1
dist	numeric or units, vector with distance value(s), in units of the coordinates

Details

arguments line, point and dist are recycled to common length when needed

Value

st_line_project returns the distance(s) of point(s) along line(s), when projected on the line(s)

st_line_interpolate returns the point(s) at dist(s), when measured along (interpolated on) the line(s)

Examples

st_line_project(st_as_sfc("LINESTRING (0 0, 10 10)"), st_as_sfc(c("POINT (0 0)", "POINT (5 5)")))
st_line_project(st_as_sfc("LINESTRING (0 0, 10 10)"), st_as_sfc("POINT (5 5)"), TRUE)
st_line_interpolate(st_as_sfc("LINESTRING (0 0, 1 1)"), 1)
st_line_interpolate(st_as_sfc("LINESTRING (0 0, 1 1)"), 1, TRUE)
# https://github.com/r-spatial/sf/issues/2542; use for geographic coordinates:
l1 <- st_as_sfc("LINESTRING (10.1 50.1, 10.2 50.2)", crs = 'OGC:CRS84')
dists = units::set_units(seq(0, sqrt(2)/10, length.out = 5), degrees)
st_line_interpolate(l1, dists)

sf documentation built on Nov. 10, 2025, 9:07 a.m.