Exercises
Practice the following exercises to revise the concepts learned in this chapter:
How did we waste computation in the
similarity_matrixfunction?Both the Last.fm and the MusicBrainz API has a count value associated with each tag, which can be taken to represent the extent to which the tag applied to the artist. By ignoring this field, in both cases, we implicitly used a count of 1 for every tag—making well-fitting tags just as important as relatively less well-fitting ones. Rewrite the code to take count into account, and weigh each tag proportionally to its count value. This will be challenging, but it will be invaluable for understanding the material. It will also boost your confidence as an R programmer once you finish. Go you!
How else might you be able to extend and improve upon our ragtag recommender system?
The Efficient market hypothesis posits that since the price of financial instruments reflects all the relevant information about its value at any given time, it is impossible...
