Calculating a distance on a map sounds straightforward, but it can be confusing how many different ways there are to do this in R.
This complexity arises because there are different ways of defining ‘distance’ on the Earth’s surface.
The Earth is spherical. So do you want to calculate distances around the sphere (‘great circle distances’) or distances on a map (‘Euclidean distances’).
Then there are barriers. For example, for distances in the ocean, we often want to know the nearest distance around islands.
Then there is the added complexity of the different spatial data types. Here we will just look at points, but these same concepts apply to other data types, like shapes.
Read on to learn these three separate techniques. H/T R-Bloggers.