Given a line and two points along that line, how can I highlight the section of the line between the two points?
The code below provides an example of a line (tr) and two points (sg) that fall on it, with the output (R/Leaflet) looking like this.
I have found examples of connecting points (e.g. here), but isn't really what I'm looking for: I need to draw/highlight the segment of the line between the two points, and not a straight line between the two points. The closest thing I could find is highlighting a section of a street (e.g. here), but I can't really apply that here (working with railway lines + I won't be able to use Google Maps).
library(tidyverse)
library(sf)
library(leaflet)
tr <- structure(
list(
SHAPE_Length = 22210.9047689,
SHAPE = structure(list(
structure(c(-3.447431, -3.426467, -3.3717497, -3.3504529,
-3.34384, -3.3063404, -3.2875194, -3.2388496, -3.1727098,
-3.136474, -3.1031447, 58.51414, 58.5140392, 58.5066418,
58.5013098, 58.4950488, 58.4901998, 58.4837109, 58.4745371,
58.4552422, 58.4512823, 58.4421872), .Dim = c(11L, 2L),
class = c("XY", "LINESTRING", "sfg"))),
n_empty = 0L, crs = structure(list(
input = "+init=epsg:4326",
wkt = "GEOGCRS[\"WGS 84\",\n
DATUM[\"World Geodetic System 1984\",\n
ELLIPSOID[\"WGS 84\",6378137,298.257223563,\n
LENGTHUNIT[\"metre\",1]],\n
ID[\"EPSG\",6326]],\n
PRIMEM[\"Greenwich\",0,\n
ANGLEUNIT[\"degree\",0.0174532925199433],\n
ID[\"EPSG\",8901]],\n
CS[ellipsoidal,2],\n
AXIS[\"longitude\",east,\n
ORDER[1],\n
ANGLEUNIT[\"degree\",0.0174532925199433,\n
ID[\"EPSG\",9122]]],\n
AXIS[\"latitude\",north,\n
ORDER[2],\n
ANGLEUNIT[\"degree\",0.0174532925199433,\n
ID[\"EPSG\",9122]]],\n
USAGE[\n
SCOPE[\"unknown\"],\n
AREA[\"World.\"],\n
BBOX[-90,-180,90,180]]]"),
class = "crs"),
class = c("sfc_LINESTRING", "sfc"),
precision = 0,
bbox = structure(c(xmin = -3.447431, ymin = 58.4421872,
xmax = -3.1031447, ymax = 58.51414), class = "bbox"))),
row.names = 1L, class = c("sf", "data.frame"),
sf_column = "SHAPE",
agr = structure(c(SHAPE_Length = NA_integer_),
.Label = c("constant", "aggregate", "identity"), class = "factor"))
sg <- structure(list(
geometry = structure(list(structure(c(-3.12213008366773, 58.4467460240336),
class = c("XY", "POINT", "sfg")),
structure(c(-3.28773441769833, 58.483750111291),
class = c("XY", "POINT", "sfg"))),
class = c("sfc_POINT", "sfc"),
precision = 0,
bbox = structure(c(xmin = -3.28773441769833, ymin = 58.4467460240336,
xmax = -3.12213008366773, ymax = 58.483750111291),
class = "bbox"),
crs = structure(list(input = "+init=epsg:4326",
wkt = "GEOGCRS[\"WGS 84\",\n
DATUM[\"World Geodetic System 1984\",\n
ELLIPSOID[\"WGS 84\",6378137,298.257223563,\n
LENGTHUNIT[\"metre\",1]],\n
ID[\"EPSG\",6326]],\n
PRIMEM[\"Greenwich\",0,\n
ANGLEUNIT[\"degree\",0.0174532925199433],\n
ID[\"EPSG\",8901]],\n
CS[ellipsoidal,2],\n
AXIS[\"longitude\",east,\n
ORDER[1],\n
ANGLEUNIT[\"degree\",0.0174532925199433,\n
ID[\"EPSG\",9122]]],\n
AXIS[\"latitude\",north,\n
ORDER[2],\n
ANGLEUNIT[\"degree\",0.0174532925199433,\n
ID[\"EPSG\",9122]]],\n
USAGE[\n
SCOPE[\"unknown\"],\n
AREA[\"World.\"],\n
BBOX[-90,-180,90,180]]]"),
class = "crs"), n_empty = 0L)),
row.names = 1:2, class = c("sf","data.frame"),
sf_column = "geometry",
agr = structure(integer(0), .Label = c("constant","aggregate", "identity"),
class = "factor", .Names = character(0)))
# Plot the stuff
leaflet() %>%
addTiles() %>%
addPolylines(data = tr) %>%
addMarkers(data = sg)
sessionInfo():
R version 4.1.1 (2021-08-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19042)
tidyverse_1.3.1
sf_1.0-3
leaflet_2.0.4.1
