R 中的最短距离

Question

I would like to know how to calculate the shortest distance between two properties (points) for my code below. There are two shapefile files, one being a points shapefile, the other a roads shapefile.

For testing, both shapefiles can be downloaded from the following website: https://github.com/JovaniSouza/JovaniSouza5/blob/master/Example.zip

library(sf)

roads <- st_read('Roads/Roads.shp')
pts <- st_read('Points/Points.shp') %>% 
  st_transform(crs=st_crs(roads))


plot(st_geometry(roads))
plot(st_geometry(pts), add = T, col = 'red', pch = 20)

Example

Answer 1

You can just use st_distance to get a distance matrix and find the minimum. I wrote a function that can process all of that and return a new sf data.frame. The data.frame will contain attributes called nearest and distance which is the index of the nearest point and the distance to that point respectively. Note the distances are in meters reflecting your projection. Your data have repeating points, so some of the points show no distance because of that. If you don't want those points you will have to remove the duplicates.

getNearest <- function(shp){
  dist <- as.data.frame(st_distance(shp))
  for (i in 1:ncol(dist)){
    rows <- seq(1:ncol(dist))
    rows <- rows[i != rows]
    shp[i, 'nearest'] <- which.min(dist[rows, i])
    shp[i, 'distance'] <- dist[which.min(dist[rows, i]), i]
  }
  return(shp)
}

pts2 <- getNearest(pts)

Answer 2

From what I understand, you are trying to measure the distance along the road to each point and it's closest point. Please see a similar workflow here: https://community.rstudio.com/t/distance-between-points-along-network-path/49596/2