Divide an sf object with LINESTRING geometry into regular segments

This function keeps the attributes. Note: results differ when use_rsgeo is TRUE: the {rsgeo} implementation will be faster. Results may not always keep returned linestrings below the segment_length value. The {rsgeo} implementation does not always return the number of segments requested due to an upstream issue in the geo Rust crate.

Usage

line_segment(
  l,
  segment_length = NA,
  n_segments = NA,
  use_rsgeo = NULL,
  debug_mode = FALSE
)

Arguments

l

A spatial lines object

segment_length

The approximate length of segments in the output (overrides n_segments if set)

n_segments

The number of segments to divide the line into. If there are multiple lines, this should be a vector of the same length.

use_rsgeo

Should the rsgeo package be used? If rsgeo is available, this faster implementation is used by default. If rsgeo is not available, the lwgeom package is used.

debug_mode

Should debug messages be printed? Default is FALSE.

Details

Note: we recommend running these functions on projected data.

See also

Other lines: angle_diff(), geo_toptail(), is_linepoint(), line2df(), line2points(), line_bearing(), line_breakup(), line_midpoint(), line_segment1(), line_via(), mats2line(), n_segments(), n_vertices(), onewaygeo(), points2line(), toptail_buff()

Examples

library(sf)
l <- routes_fast_sf[2:4, "ID"]
l_seg_multi <- line_segment(l, segment_length = 1000, use_rsgeo = FALSE)
l_seg_n <- line_segment(l, n_segments = 2)
#> Setting n_segments to 2 for all lines
l_seg_n <- line_segment(l, n_segments = c(1:3))
# Number of subsegments
table(l_seg_multi$ID)
#> 
#> 3 4 5 
#> 3 3 2 
plot(l_seg_multi["ID"])

plot(l_seg_multi$geometry, col = seq_along(l_seg_multi), lwd = 5)

round(st_length(l_seg_multi))
#> Units: [m]
#> [1] 1013 1014  955  875  770  647  986  881
# rsgeo implementation (default if available):
if (rlang::is_installed("rsgeo")) {
  rsmulti = line_segment(l, segment_length = 1000, use_rsgeo = TRUE)
  plot(rsmulti["ID"])
}

# Check they have the same total length, to nearest mm:
# round(sum(st_length(l_seg_multi)), 3) == round(sum(st_length(rsmulti)), 3)
# With n_segments for 1 line:
l_seg_multi_n <- line_segment(l[1, ], n_segments = 3, use_rsgeo = FALSE)
l_seg_multi_n <- line_segment(l$geometry[1], n_segments = 3, use_rsgeo = FALSE)
l_seg_multi_n <- line_segment(l$geometry[1], n_segments = 3, use_rsgeo = TRUE)
# With n_segments for all 3 lines:
l_seg_multi_n <- line_segment(l, n_segments = 2)
#> Setting n_segments to 2 for all lines
nrow(l_seg_multi_n) == nrow(l) * 2
#> [1] TRUE