Checking whether CRS is geographic coordinate system or projected coordinate system using R

Question

I am writing a generic script that would calculate areas covered by different classes in a categorical raster in R. I would like to provide two functions; one for use when the CRS of the raster is geographic (long, lat), and one to use when the CRS is projected.

Is there a way I can check that?

I imagine there is a property of the CRS string I'd check in an if() statement for that

Answer 1

The raster package has a function isLonLat for this purpose. Analogous for vector data, there is the st_is_longlat function from sf.