We might try at this point to keep adding features to our model in an attempt to increase its explanatory power.
For example, we also have a
"Date of birth" column and we may be tempted to try and include this too. It is a date, but we could easily convert it into a number suitable for use in regression. We could do this simply by extracting the year from their birth date using the
(defn to-year [str] (-> (coerce/from-date str) (time/year))) (defn ex-3-27  (let [data (->> (swimmer-data) (i/add-derived-column "Dummy MF" ["Sex"] dummy-mf) (i/add-derived-column "Year of birth" ["Date of birth"] to-year)) x (->> data (feature-matrix ["Height, cm" "Age" "Dummy MF" "Year of birth"]) (add-bias)) y (->> (i/$ "Weight" data) ...