Plotting dynamic maps with mapview

Cool mapping features in R with mapview.

I’ve spent a lot of time working with spatial data recently, and came across a cool tool to display maps that I thought was worth writing about. Here are some of the cool features you can find in mapview.

I’ll be using the included breweries, and franconia datasets to show off some of the features I found useful for making dynamic maps.

Overlaying points on a polygon

Mapview can stack maps on each other with ease. For example, we can take the shape files from the franconia data, and overlay the breweries’ coordinates on the same map. Notice when you click on either a point or polygon you get information about the specific data.

pacman::p_load(mapview, leafsync, leaflet.extras2, dplyr)

regions = mapview(franconia,
  zcol = "NAME_ASCI",
  legend = FALSE
)

brew = mapview(breweries,
  legend = FALSE,
  cex = breweries$number.of.types, # size based on number of beers
  col.regions = "white") # color points white 

regions + brew

Comparing two maps side by side

One of the cooler features I’ve come across comes from leafsync::sync(), which allows you to place two mapview maps next to each other, and mirror the location of your mouse from one map to the next. Admittedly this isn’t the best usecase for this comparison, but lets compare the maps showing breweries founded before the year 1800 and after.

CUTOFF = 1800
map_pre = regions + 
  mapview(breweries |>
            filter(founded < CUTOFF),
          legend = FALSE,
          col.regions = "blue")

map_post = regions + 
  mapview(breweries |>
            filter(founded >= CUTOFF),
          legend = FALSE,
          col.regions = "green")

sync(map_pre, map_post)

Additionally, you can add a slider to compare the two maps in the same map.

map_pre | map_post

I’m sure there is plenty more use cases and functionality available within mapview, but these are some of the cases I’ve come across that I’ve found helpful in my workflow.