Routes

With TargomoR you can access routing data all over the world in a convenient, nested structure, letting you focus on the start and end points. Visualising a route can add the finishing touch to a map or shiny application!

Getting the Data

For the routing service, getTargomoRoutes() returns a named nested list. The names are the travel modes given in the travelType option (specifying multiple modes will make multiple calls to the API).

Within each travel mode is a list of the returned routes - one for each source/target combination where a route has been found. Each route is a data.frame, containing the source and target IDs, and a features data.frame of a simple feature collection (class ‘sf’). This contains:

• points - the source and target points of the route, as POINT objects.
• walk, bike, car, transit - the routes by each mode of transport (where requested) as LINESTRING objects.
• transfers - points where public transport changes (e.g. change bus) as POINT objects.

Each SFC also contains fields giving the start and end names of the LINESTRINGs, the length of time the section takes and the distance in metres.

For example, for two routes by bike, the output will look like:

# set source and target data
source <- data.frame(id = "Big Ben", lat = 51.5007, lng = -0.1246)
target <- data.frame(id = c("Tower Bridge", "Covent Garden"),
                     lat = c(51.5055, 51.5117),
                     lng = c(-0.0754, -0.1246))

# query the API
routes <- getTargomoRoutes(source_data = source, target_data = target,
                           source_lat = ~lat, source_lng = ~lng,
                           target_lat = ~lat, target_lng = ~lng,
                           source_id = ~id, target_id = ~id,
                           options = targomoOptions(travelType = "bike"))

# examine the structure
str(routes, max.level = 3, give.attr = FALSE)
#> List of 1
#>  $ bike:List of 2
#>   ..$ :Classes 'tbl_df', 'tbl' and 'data.frame': 3 obs. of  3 variables:
#>   .. ..$ sourceId: chr [1:3] "Big Ben" "Big Ben" "Big Ben"
#>   .. ..$ targetId: chr [1:3] "Tower Bridge" "Tower Bridge" "Tower Bridge"
#>   .. ..$ features:Classes 'sf' and 'data.frame': 3 obs. of  9 variables:
#>   ..$ :Classes 'tbl_df', 'tbl' and 'data.frame': 3 obs. of  3 variables:
#>   .. ..$ sourceId: chr [1:3] "Big Ben" "Big Ben" "Big Ben"
#>   .. ..$ targetId: chr [1:3] "Covent Garden" "Covent Garden" "Covent Garden"
#>   .. ..$ features:Classes 'sf' and 'data.frame': 3 obs. of  9 variables:

The features object for the first route will look like:

routes$bike[[1]]$features
#> Simple feature collection with 3 features and 8 fields
#> geometry type:  GEOMETRY
#> dimension:      XY
#> bbox:           xmin: -0.1245714 ymin: 51.50074 xmax: -0.0743502 ymax: 51.51129
#> epsg (SRID):    4326
#> proj4string:    +proj=longlat +datum=WGS84 +no_defs
#>   startName   length     targetId travelTime                       geometry
#> 1    source 4453.667         <NA>       1371 LINESTRING (-0.0743917 51.5...
#> 2      <NA>       NA Tower Bridge         NA    POINT (-0.0743917 51.50643)
#> 3      <NA>       NA         <NA>         NA    POINT (-0.1245714 51.50074)
#>   endName sourceId travelType   name
#> 1  target     <NA>       BIKE   <NA>
#> 2    <NA>     <NA>       <NA> Target
#> 3    <NA>  Big Ben       <NA> Source

Integration with Leaflet

The TargomoR package lets you easily visualise your route data. You can either:

• draw an existing routes object with drawTargomoRoutes(), or;
• combine the API call and drawing with addTargomoRoutes(), or;
• write your own drawing function using leaflet::addPolylines

In this example, we use addTargomoRoutes() to show the cycling routes above.

leaflet() %>% 
  addTargomoTiles() %>% 
  addTargomoRoutes(source_data = source, source_id = ~id,
                   target_data = target, target_id = ~id,
                   options = targomoOptions(travelType = "bike"))
#> Assuming "lng" and "lat" are longitude and latitude, respectively
#> Assuming "lng" and "lat" are longitude and latitude, respectively

Drawing Options

Using addTargomoRoutes() or drawTargomoRoutes() you can customise the way the routes appear on the map with a call to routeDrawOptions(). The options available are:

Option	Default	Meaning
showMarkers	TRUE	Should the source/target points be marked?
showTransfers	TRUE	Should the public transport changes be marked?
{travel}Color	car = "blue", bike = "orange", walk = "green", transit = "red"	The route line color
{travel}Weight	5 for all travel types	The route line width
{travel}DashArray	walk = "1,10", other = NULL	The route dash pattern
transferColor	"blue"	The color for transfer circle markers
transferRadius	10	The radius for transfer circle markers

Changing these, we could for instance make the map above but with purple dotted lines (and here we’ll use drawTargomoRoutes()):

leaflet() %>% 
  addTargomoTiles() %>% 
  drawTargomoRoutes(routes = routes, 
                    drawOptions = routeDrawOptions(
                      bikeColour = "purple",
                      bikeDashArray = "10,15"
                    ))