I am working with a shapefile in R that is made up of 48 polygons. It is a map of Sweden with a line plotted to denote a biological boundary between north and south. I want to figure out the latitude of the line (see plot) but I cannot figure out how to extract that information from the shapefile.
I am wondering how to go about this. Can I plot each polygon separately to see if one/multiple polygons make up this line?