To summarize, in this chapter you learned how to interpolate point data in space to produce continuous rasters using four different methods. The first of these, nearest-neighbor interpolation, we coded ourselves, while the other three (IDW, OK, and UK) were applied using functions in the gstat and automap packages. You also learned how to perform LOOCV to calculate RMSE and assess prediction accuracy. Finally, we saw two examples of how to automate a complex procedure to perform it repeatedly over an array of parameter sets.

In the next chapter, you are going to learn how to produce more elaborate plots involving spatial data in R with ggplot2.