st_line_sample: Sample points on a linear geometry

Description Usage Arguments Examples

View source: R/geom.R

Description

Sample points on a linear geometry

Usage

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st_line_sample(x, n, density, type = "regular", sample = NULL)

Arguments

x

object of class sf, sfc or sfg

n

integer; number of points to choose per geometry; if missing, n will be computed as round(density * st_length(geom)).

density

numeric; density (points per distance unit) of the sampling, possibly a vector of length equal to the number of features (otherwise recycled); density may be of class units.

type

character; indicate the sampling type, either "regular" or "random"

sample

numeric; a vector of numbers between 0 and 1 indicating the points to sample - if defined sample overrules n, density and type.

Examples

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ls = st_sfc(st_linestring(rbind(c(0,0),c(0,1))),
	st_linestring(rbind(c(0,0),c(10,0))))
st_line_sample(ls, density = 1)
ls = st_sfc(st_linestring(rbind(c(0,0),c(0,1))),
 st_linestring(rbind(c(0,0),c(.1,0))), crs = 4326)
try(st_line_sample(ls, density = 1/1000)) # error
st_line_sample(st_transform(ls, 3857), n = 5) # five points for each line
st_line_sample(st_transform(ls, 3857), n = c(1, 3)) # one and three points
st_line_sample(st_transform(ls, 3857), density = 1/1000) # one per km
st_line_sample(st_transform(ls, 3857), density = c(1/1000, 1/10000)) # one per km, one per 10 km
st_line_sample(st_transform(ls, 3857), density = units::set_units(1, 1/km)) # one per km
# five equidistant points including start and end:
st_line_sample(st_transform(ls, 3857), sample = c(0, 0.25, 0.5, 0.75, 1))

sf documentation built on July 24, 2019, 5:05 p.m.