Add how to save serialized objects to course

[ttimbers]

Model objects that are trained/fit in one script, and then need to be used again later in another script can and should be saved as binary files. In R, the format is .RDS and we use the functions saveRDS() and readRDS() to do this. In python, the format is .pickle and we use the functions pickle.dump() and pickle.load() from the pickle package.

example of saveRDS()

saveRDS(final_knn_model, "results/final_knn_model.rds")

example of readRDS()

final_knn_model <- readRDS("results/final_knn_model.rds")

example of pickle.dump()

import pickle
pickle.dump(final_knn_model, open("results/final_knn_model.pickle", "wb"))

example of pickle.load()

import pickle
final_knn_model = pickle.load(open("results/final_knn_model.pickle", "rb"))