OWFeatureStatistics: Fixup warnings when calculating dispersion

Author: pavlin-policar

Orange/widgets/data/owfeaturestatistics.py

@@ -39,6 +39,14 @@ def _categorical_entropy(x):
     return np.fromiter((ss.entropy(pk) for pk in p), dtype=np.float64)
 
 
+def coefficient_of_variation(x: np.ndarray) -> np.ndarray:
+    mu = ut.nanmean(x, axis=0)
+    mask = ~np.isclose(mu, 0, atol=1e-12)
+    result = np.full_like(mu, fill_value=np.inf)
+    result[mask] = np.sqrt(ut.nanvar(x, axis=0)[mask]) / mu[mask]
+    return result
+
+
 def format_time_diff(start, end, round_up_after=2):
     """Return an approximate human readable time difference between two dates.
 
@@ -228,7 +236,7 @@ def __compute_statistics(self):
         self._dispersion = self.__compute_stat(
             matrices,
             discrete_f=_categorical_entropy,
-            continuous_f=lambda x: np.sqrt(ut.nanvar(x, axis=0)) / ut.nanmean(x, axis=0),
+            continuous_f=coefficient_of_variation,
         )
         self._missing = self.__compute_stat(
             matrices,