How to show path and distance on map with leaflet?

Question

I would like to show the distance between two locations using the leaflet package in a shiny app. I don't know how to do it. A line should connect two points on a map and display the distance on it. Please find the sample image, this describes my expectation:

Answer 1

Try the below:

library(leaflet)
library(osrm)

route = osrmRoute(c(115.6813467,-32.0397559), c(150.3715249,-33.8469759), overview = 'full')
# route_simple = osrmRoute(c(115.6813467,-32.0397559), c(150.3715249,-33.8469759), overview = 'simplified')
route_summary = osrmRoute(c(115.6813467,-32.0397559), c(150.3715249,-33.8469759), overview = FALSE)

leaflet() %>% addTiles() %>% 
  addMarkers(c(115.6813467,150.3715249), c(-32.0397559,-33.8469759)) %>% 
  addPolylines(route$lon,route$lat, 
               label = paste(round(route_summary[1]/60), 'hr - ', round(route_summary[2]), 'km'), 
               labelOptions = labelOptions(noHide = TRUE))

leaflet() %>% addTiles() %>% 
  addMarkers(c(115.6813467,150.3715249), c(-32.0397559,-33.8469759)) %>% 
  addPolylines(route$lon,route$lat, 
               popup = paste(round(route_summary[1]/60), 'hr', br(), round(route_summary[2]), 'km'))

I added route_simple in the code above but didn't use it. It just saves less points on the route so it's less detailed but runs quicker. Feel free to play around. I also used a popup instead of a label in my second example. You need to click on the route to open it.

Label Example

Popup Example

If you want a shiny app then see below:

library(leaflet)
library(osrm)

route = osrmRoute(c(115.6813467,-32.0397559), c(150.3715249,-33.8469759), overview = 'full')
# route_simple = osrmRoute(c(115.6813467,-32.0397559), c(150.3715249,-33.8469759), overview = 'simplified')
route_summary = osrmRoute(c(115.6813467,-32.0397559), c(150.3715249,-33.8469759), overview = FALSE)

library(shiny)

ui <- fluidPage(
  leafletOutput('map')
)

server <- function(input, output, session) {
  output$map <- renderLeaflet({
    leaflet() %>% addTiles() %>% 
      addMarkers(c(115.6813467,150.3715249), c(-32.0397559,-33.8469759)) %>% 
      addPolylines(route$lon,route$lat, 
                   label = paste(round(route_summary[1]/60), 'hr - ', round(route_summary[2]), 'km'), 
                   labelOptions = labelOptions(noHide = TRUE))
  })
}

shinyApp(ui, server)