Leaflet + Proj4Leaflet

library(leaflet)

Default SPherical Mercator Projection specified explicitly

leaflet(
  options =
    leafletOptions(crs=leafletCRS(crsClass='L.CRS.EPSG3857'))) %>% addTiles()

Gothenberg, Sweeden in default projection

leaflet() %>%
  addTiles() %>% setView(11.965, 57.704, 16)

Gothenberg, Sweeden in local projection

leaflet(
  options =
    leafletOptions(
      worldCopyJump = FALSE,
      crs=leafletCRS(
        crsClass="L.Proj.CRS",
        code='EPSG:3006',
        proj4def='+proj=utm +zone=33 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs',
        resolutions = c(
          8192, 4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1, 0.5 ),
        origin =c(0, 0))
      )) %>%
  addTiles(
    urlTemplate = 'http://api.geosition.com/tile/osm-bright-3006/{z}/{x}/{y}.png',
    attribution = 'Map data &copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap contributors</a>, Imagery &copy; 2013 <a href="http://www.kartena.se/">Kartena</a>',
    options = tileOptions(minZoom=0,maxZoom=14,continuousWorld = TRUE)) %>%
  setView(11.965, 57.704, 13)

## Mollweide Projection The code is adaptation of this.

library(sp)

## Warning: package 'sp' was built under R version 3.3.2

## Loading required package: methods

srcURL <- "https://cdn.rawgit.com/turban/Leaflet.Graticule/master/examples/lib/countries-110m.js"
v8 <- V8::v8()
v8$source(srcURL)
geoJSON <- geojsonio::as.json(v8$get('countries'))
spdf <- geojsonio::geojson_sp(geoJSON)
sp::proj4string(spdf) # We need our data to be in WGS84 a.k.a EPSG4326 i.e. just latlong

## [1] "+proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0"

# Leaflet will project the polygons/lines/markers to the target CRS before it maps them.
leaflet(options =
          leafletOptions(maxZoom = 5,
               crs=leafletCRS(crsClass="L.Proj.CRS", code='ESRI:53009',
                        proj4def= '+proj=moll +lon_0=0 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs',
                        resolutions = c(65536, 32768, 16384, 8192, 4096, 2048)
                       ))) %>%
  addGraticule(style= list(color= '#999', weight= 0.5, opacity= 1)) %>%
  addGraticule(sphere = TRUE, style= list(color= '#777', weight= 1, opacity= 0.25)) %>%
  addPolygons(data=spdf, weight = 1, color = "#ff0000")

L.CRS.Simple example. For now the image is specified via onRender and native JS call because we haven’t coded the L.ImageLayer part yet.

bounds <- c(-26.5,-25, 1021.5,1023)
leaflet(options= leafletOptions(
  crs=leafletCRS(crsClass='L.CRS.Simple'),
  minZoom= -5,
  maxZoom = 5)) %>%
  fitBounds(bounds[1], bounds[2], bounds[3], bounds[4]) %>%
  setMaxBounds(bounds[1], bounds[2], bounds[3], bounds[4]) %>%
  htmlwidgets::onRender("
  function(el, t) {
    var myMap = this;
    var bounds = myMap.getBounds();
    var image = new L.ImageOverlay(
                      'http://leafletjs.com/examples/crs-simple/uqm_map_full.png',
                      bounds);
    image.addTo(myMap);
  }")

Albers USA with moved Alaska and Hawaii with some fancy effects. You need albersusa for this. devtools::install_github('hrbrmstr/albersusa')

library(sp)
library(albersusa)
spdf <- rmapshaper::ms_simplify(usa_composite())
pal <- colorNumeric(
  palette = "Blues",
  domain = spdf@data$pop_2014
)

bounds <- c(-125, 24 ,-75, 45)

leaflet(
  options=
    leafletOptions(
      worldCopyJump = FALSE,
      crs=leafletCRS(
        crsClass="L.Proj.CRS",
        code='EPSG:2163',
        proj4def='+proj=laea +lat_0=45 +lon_0=-100 +x_0=0 +y_0=0 +a=6370997 +b=6370997 +units=m +no_defs',
        resolutions = c(65536, 32768, 16384, 8192, 4096, 2048,1024, 512, 256, 128)
      ))) %>%
  fitBounds(bounds[1], bounds[2], bounds[3], bounds[4]) %>%
  setMaxBounds(bounds[1], bounds[2], bounds[3], bounds[4]) %>%
  addPolygons(data=spdf, weight = 1, color = "#000000",
              fillColor=~pal(pop_2014),
              fillOpacity=0.7,
              label=~stringr::str_c(name,' ', pop_2014),
              labelOptions= labelOptions(direction = 'auto'),
              highlightOptions = highlightOptions(
                color='#00ff00', opacity = 1, weight = 2, fillOpacity = 1,
                bringToFront = TRUE, sendToBack = TRUE) )