Calculate the minimum and maximum angles between two sf LINESTRING objects

Function for calculating the minimum and maximum angles between two intersecting sf MULTILINESTRING or LINESTRING objects.

Usage

desplim_angles(input_lines, reference_lines, cast_substring = TRUE)

Arguments

input_lines: object of class sf of type LINESTRING or MULTILINESTRING.
reference_lines: object of class sf of type LINESTRING or MULTILINESTRING.
cast_substring: logical; should the input linestrings be cast to substring? Default is TRUE.

Value

An sf object with the geometries from input_lines with added columns containing the values of the minimum and maximum angle.

Details

If the input and reference lines are already cast to substring, the function can be sped up, notably by setting cast_substring to FALSE for larger geometries.

Examples

# Create input and reference lines
input_line <- sf::st_linestring(matrix(
  c(-1, 0, 0, 0, 1, 0),
  ncol = 2,
  byrow = TRUE
))
ref_line <- sf::st_linestring(matrix(
  c(0, -1, 0, 0, -0.5, 1),
  ncol = 2,
  byrow = TRUE
))
input_sf <- sf::st_sf(geom = sf::st_sfc(input_line), crs = 32613)
ref_sf <- sf::st_sf(geom = sf::st_sfc(ref_line), crs = 32613)

# Calculate angles
angles_sf <- desplim_angles(input_lines = input_sf, reference_lines = ref_sf)
print(angles_sf)
#> Simple feature collection with 2 features and 2 fields
#> Geometry type: LINESTRING
#> Dimension:     XY
#> Bounding box:  xmin: -1 ymin: 0 xmax: 1 ymax: 0
#> Projected CRS: WGS 84 / UTM zone 13N
#>                 geometry min_angle max_angle
#> 1 LINESTRING (-1 0, 0 0)  63.43495   90.0000
#> 2  LINESTRING (0 0, 1 0)  90.00000  116.5651

# Plot
plot(sf::st_geometry(input_sf), col = "tomato3", lwd = 2)
plot(sf::st_geometry(ref_sf), add = TRUE, col = "slateblue3", lwd = 2)
text(-0.1, 0.1, paste0(round(angles_sf$min_angle[[1]], 1), "°"), pos = 2)
text(-0.1, -0.1, paste0(round(angles_sf$max_angle[[1]], 1), "°"), pos = 2)
text(0.1, 0.1, paste0(round(angles_sf$max_angle[[2]], 1), "°"), pos = 4)
text(0.1, -0.1, paste0(round(angles_sf$min_angle[[2]], 1), "°"), pos = 4)