library(leaflet)

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

Default Minimap

l %>% addTiles() %>% addMiniMap()

Different basemap for the minimap and togglable

l %>% addProviderTiles(providers$Esri.WorldStreetMap) %>%
  addMiniMap(
             tiles = providers$Esri.WorldStreetMap,
             toggleDisplay = T)

Slightly advanced use case Change minimap basemap to match main map’s basemap This approach will work for basemaps added via addProviderTiles But not for one’s added with addTiles using a URL schema.

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

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

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

Another advanced use case Minimap with markers. Note the use of ‘group’ ID to find markers in main map and add corresponding CircleMarkers in minimap. The V8 part is simply to read the JSON embeded in the Javascript.
For a geojson file jsonlite::fromfromJSON() or geojsonio::regeojson_read() will do

jsURL <- 'https://rawgit.com/Norkart/Leaflet-MiniMap/master/example/local_pubs_restaurant_norway.js'
v8 <- V8::v8()
v8$source(jsURL)
geoJson <- geojsonio::as.json(v8$get('pubsGeoJSON'))

# This is the kicker, convert geojson to a Spatial object.
# This then allows us to use formulas in our markers, polygons etc.
spdf <- geojsonio::geojson_sp(geoJson)

icons <- awesomeIconList(
  pub = makeAwesomeIcon(icon='glass', library='fa', markerColor = 'red'),
  restaurant = makeAwesomeIcon(icon='cutlery', library='fa', markerColor = 'blue')
)

leaflet() %>% addTiles() %>%
  setView(10.758276373601069, 59.92448055859924, 13) %>%
  addAwesomeMarkers(data=spdf,
             label=~stringr::str_c(amenity,': ', name),
             icon = ~icons[amenity],
             options = markerOptions(riseOnHover = TRUE, opacity = 0.75),
             group = 'pubs') %>%
  addMiniMap() %>%
  htmlwidgets::onRender("
    function(el, t) {
      var myMap = this;

      var pubs = myMap.layerManager._byGroup.pubs;
      var pubs2 = new L.FeatureGroup();

      for(pub in pubs) {
        var m = new L.CircleMarker(pubs[pub]._latlng, {radius: 2});
        pubs2.addLayer(m);
      }
      var layers = new L.LayerGroup([myMap.minimap._layer, pubs2]);
      myMap.minimap.changeLayer(layers);
    }")

Finally combine the approaches in last 2 examples Minimap w/ changable layers and circle markers.

m <- leaflet()
esri %>%
  purrr::walk(function(x) m <<- m %>% addProviderTiles(x,group=x))
m %>%
  setView(10.758276373601069, 59.92448055859924, 13) %>%
  addAwesomeMarkers(data=spdf,
             label=~stringr::str_c(amenity,': ', name),
             icon = ~icons[amenity],
             options = markerOptions(riseOnHover = TRUE, opacity = 0.75),
             group = 'pubs') %>%
  addLayersControl(
    baseGroups = names(esri),
    options = layersControlOptions(collapsed = FALSE)
  ) %>%
  addMiniMap(tiles = esri[[1]],
             toggleDisplay = T) %>%
  htmlwidgets::onRender("
    function(el, t) {
      var myMap = this;

      var pubs = myMap.layerManager._byGroup.pubs;
      var pubs2 = new L.FeatureGroup();

      for(pub in pubs) {
        var m = new L.CircleMarker(pubs[pub]._latlng, {radius: 2});
        pubs2.addLayer(m);
      }
      var layers = new L.LayerGroup([myMap.minimap._layer, pubs2]);

      myMap.minimap.changeLayer(layers);

      myMap.on('baselayerchange',
        function (e) {
          myMap.minimap.changeLayer(
            new L.LayerGroup([L.tileLayer.provider(e.name), pubs2]));
        });
    }")