Fix growth when current period is 0

src/metabase/feature_extraction/feature_extractors.clj

@@ -49,13 +49,12 @@
 (defn growth
   "Relative difference between `x1` an `x2`."
   [x2 x1]
-  (when (and x1 x2)
+  (when (and x1 x2 (not (zero? x1)))
     (let [x2 (double x2)
           x1 (double x1)]
       (cond
         (every? neg? [x1 x2])     (growth (- x1) (- x2))
         (and (neg? x1) (pos? x2)) (- (growth x1 x2))
-        (nil? x1)                 nil
         :else                     (/ (* (if (neg? x1) -1 1) (- x2 x1)) x1)))))
 
 (defn- merge-juxt

test/metabase/feature_extraction/feature_extractors_test.clj

@@ -20,12 +20,20 @@
    1.0
    -0.5
    -5.0
-   5.0]
+   5.0
+   2.0
+   nil
+   nil
+   nil]
   [(growth 123 100)
    (growth -0.1 -0.2)
    (growth -0.4 -0.2)
    (growth -0.4 0.1)
-   (growth 0.1 -0.4)])
+   (growth 0.1 -0.4)
+   (growth Long/MAX_VALUE Long/MIN_VALUE)
+   (growth 0.1 nil)
+   (growth nil 0.5)
+   (growth 0.5 0.0)])
 
 (expect
   [{:foo 2