bang.R

library(sf)
library(elevatr)
library(raster)
library(tanaka)
# a polygon of bangalore
bangalore <- st_read("export.geojson")
elevation <- get_elev_raster(bangalore, z = 10)
bangalore_elevation <- trim(mask(elevation, bangalore))

# inspect min and max values
summary(bangalore_elevation)

# get contours
bangalore_contour <- tanaka_contour(bangalore_elevation, 
                                    breaks = seq(750, 1000, 25))
# define margins and facets
par(mfrow = c(1,2), mar = c(0,0,0,0))
# plot raster and contour
plot(bangalore_elevation, axes = F, box = FALSE, legend = FALSE)
plot(st_geometry(bangalore_contour), add = TRUE, 
     col = NA, border = "grey20", lwd = .5)

# plot tanaka
tanaka(bangalore_contour,
       col = hcl.colors(n = nrow(bangalore_contour), 
                        palette = "Cividis"), 
       legend.pos = "topright")