Leaflet R derivePolygons missing lat missing long

Question

I am trying to plot the site of some disease-events data on a map.

I use this to import the data:

ByTown<-readOGR(dsn=\"C:/temp/lyme/Towns\", lay         


        

Answer 1

Don't forget to add the data = ... variable name in addPolygons() if you don't provide it in the leaflet() call. I received the same error and spent hours looking for a solution :(.

This does not work:

leaflet() %>%
  addTiles() %>%
  addPolygons(ByTown)

and returns:

Error in derivePolygons(data, lng, lat, missing(lng), missing(lat), "addPolygons") : 
  addPolygons must be called with both lng and lat, or with neither.

This works:

leaflet() %>%
  addTiles() %>%
  addPolygons(data = ByTown)

Answer 2

The addPolygons function either requires you to define the columns of latitude & longitude, OR it will try and derive them from the data you provide.

Given you haven't specified the lat/lon columns, it tries to work out which ones they are. In your case, it couldn't find them. This is mainly due to your data not being in lat/lon format.

Therefore, you'll need to transform your data to use a lat/lon projection, something like (untested)

nByTown_latlon <- spTransform(nByTown, CRS("+proj=longlat +datum=WGS84"))