raster_contours_leaflet.r

#devtools::install_github('rstudio/leaflet')

library(leaflet)
library(raster)

## fake a raster
r <- raster(volcano)
## this volcano is in NZ, but we are ignoring that with huge abandon
extent(r) <- extent(100, 150, -42, -15)
projection(r) <- "+init=epsg:4326"
n <- 768
set.seed(1)
pts <- cbind(runif(n, xmin(r), xmax(r)), runif(n, ymin(r), ymax(r)))

## create a trad MASS xyz list "raster"
## and convert to raster
kde <- raster(MASS::kde2d(pts[, 1], pts[, 2]))


## contour the raster (picks defaults, same as ?contour)
cont <- rasterToContour(kde)

## give to leaflet
leaflet() %>% addTiles() %>% addPolylines(data = cont)