Creating a single pixel wide raster along the coastline or another edge

At one point during my PhD I needed a single pixel of raster values along the coastline. In order to get this I used the following code in R:

library(sdmpredictors)
library(raster)

coast_mask <- function(layer) {
  edges <- raster::boundaries(raster(layer, layer=1), type="inner")
  values <- getValues(edges)
  is.na(values) | values == 0
}

l <- load_layers("BO_sstmean", equalarea = FALSE)

mask <- coast_mask(l)
l[mask] <- NA

plot(l, col=rev(heat.colors(255)))

Source code available on GitHub at https://github.com/samuelbosch/blogbits/blob/master/misc/coastalraster.R

Main R Packages used:

• sdmpredictors
• raster