Leaflet Measure

addMeasure functions adds a control on the map that you can use to measure distance/area on your map.

library(leaflet)
leaflet() %>% addTiles() %>%
  # central park
  fitBounds(-73.9, 40.75, -73.95,40.8) %>%
  addMeasure()

Adding a Graticule

leaflet() %>%
  addTiles() %>%
  setView(0,0,2) %>%
  addGraticule(interval = 20,
               style = list(color='#000000', weight=1))

Adding a Day/Night indicator

leaflet() %>% setView(0,0,1) %>%
  addTiles() %>% addTerminator(resolution=1)

Adding a Minimap

leaflet() %>% setView(0,0,3) %>%
  addProviderTiles(providers$Esri.WorldStreetMap) %>%
  addMiniMap(tiles = providers$Esri.WorldStreetMap,
             toggleDisplay = T)

Custom buttons and Toolbars

There are two functions addEasyButton and addEasyButtonBar which allow you to add your own functions and define the actions to execute when clicked. Here we show a simple example to reset the map to specific view.

leaflet() %>% setView(-74.0059,40.7128,10) %>% addTiles() %>%
  addEasyButton(easyButton(
    icon='fa-globe', title='Zoom to Level 5',
    onClick=JS("function(btn, map){ map.setZoom(5);}")))

htmlwidget’s onRender function

The htmlwidget::onRender function can be used to add custom behavior to the leaflet map using native Javascript. This is a some what advanced use case and requires you to know Javascript. Using onRender you can customize your map’s behavior using any of the APIs as defined in the leafletJS documentation.

Below is an example where we sync the base layer of the mini-map with the baselayer of the main map, using the ‘baselayerchange’ event.

l <- leaflet() %>% setView(0,0,3)

esri <- providers %>%
  purrr::keep(~ grepl('^Esri',.))

esri %>%
  purrr::walk(function(x) l <<- l %>% addProviderTiles(x,group=x))

l %>%
  addLayersControl(
    baseGroups = names(esri),
    options = layersControlOptions(collapsed = FALSE)
  ) %>%
  addMiniMap(tiles = esri[[1]],
             toggleDisplay = T, position = 'bottomleft') %>%
  htmlwidgets::onRender("
    function(el, x) {
      var myMap = this;
      myMap.on('baselayerchange',
        function (e) {
          myMap.minimap.changeLayer(L.tileLayer.provider(e.name));
        })
    }")