How do I use a Simple Feature Collection (sfc) from the sf package with the elevatr package to load elevation data?

Question

I'm trying to load elevation data from AWS using the elevatr package, with a region defined as a Simple Features Collection from the sf package. Here's a simple example:

library(elevatr)
library(sf)
library(USAboundaries)

counties <- us_counties(map_date = "1930-01-01", resolution = "high", states = c("NY"))
elevation <- get_elev_raster(counties$geometry, z = 9, src = "aws")

This gives an error:

Error in if (attributes(class(locations)) %in% c("raster", "sp")) { : 
  argument is of length zero
In addition: Warning messages:
1: In if (class(locations) == "data.frame") { :
  the condition has length > 1 and only the first element will be used
2: In if (class(locations) == "SpatialPoints") { :
  the condition has length > 1 and only the first element will be used
3: In if (class(locations) == "SpatialPointsDataFrame") { :
  the condition has length > 1 and only the first element will be used

Presumably because the sfc is a collection of polygons and MULTIPOINT objects, which aren't supported by the get_elev_raster function of the elevatr package.

Is there any way to use these packages together? With the end result being an sfc object that also has various forms of elevation data for each point?

---

_{I'm getting the data this way because it doesn't seem like the st_read function from the sf package can read ESRI ASCII files.}

Answer 1

counties <- us_counties(map_date = "1930-01-01", resolution = "high", states = c("NY"))

this has created an sf object, but:

elevation <- get_elev_raster(counties$geometry, z = 9, src = "aws")

this expects an sp object. Convert sf to sp with:

counties_sp = as(counties, "Spatial")

then this should work:

elevation = get_elev_raster(counties_sp, z=..... etc.....)

I cant replicate your code at the moment because the USABoundariesData package is refusing to install...