I have a raster file from the FAO's Global Agro-ecological Zone database ( http://gaez.fao.org/Main.html#) which gives the yields of specific crops in 5' grid cells. I would like to assign a country name to each of these grid cell (obviously drop the cells that have no yield data or lie in the oceans). I was thinking of using GADM but I don't know how to reconcile these two sources.
Ultimately, I want to create a data frame with the following columns:
Grid cell ID | Longitude | Latitude | Yield (from raster) | Country
I'm quite clueless as to where to even begin. For some broader context, I'm trying to follow this paper: https://economics.mit.edu/files/7536 by summing up the crop production in each country from the grid cells.