normalize: Fix failing tests due to decimals

Author: pavlin-policar

Orange/preprocess/normalize.py

@@ -52,8 +52,14 @@ def normalize_by_sd(self, dist, var: ContinuousVariable) -> ContinuousVariable:
             compute_val = Norm(var, avg, 1 / sd)
         else:
             compute_val = Norm(var, 0, 1 / sd)
-        num_decimals = var.number_of_decimals + int(np.ceil(np.log10(sd)))
-        num_decimals = max(num_decimals, 0)  # num decimals can't be negative
+
+        # When dealing with integers, and multiplying by something smaller than
+        # 1, the number of decimals should be decreased, but this integer will
+        # likely turn into a float, which should have some default number of
+        # decimals
+        num_decimals = var.number_of_decimals + int(np.round(np.log10(sd)))
+        num_decimals = max(num_decimals, 3)  # num decimals can't be negative
+
         return var.copy(compute_value=compute_val, number_of_decimals=num_decimals)
 
     def normalize_by_span(self, dist, var: ContinuousVariable) -> ContinuousVariable:
@@ -65,6 +71,9 @@ def normalize_by_span(self, dist, var: ContinuousVariable) -> ContinuousVariable
             compute_val = Norm(var, dmi, 1 / diff)
         else:
             compute_val = Norm(var, (dma + dmi) / 2, 2 / diff)
-        num_decimals = var.number_of_decimals + int(np.ceil(np.log10(diff)))
-        num_decimals = max(num_decimals, 0)  # num decimals can't be negative
-        return var.copy(compute_value=compute_val, number_of_decimals=num_decimals)
+        if not np.isnan(diff):
+            num_decimals = var.number_of_decimals + int(np.ceil(np.log10(diff)))
+            num_decimals = max(num_decimals, 0)  # num decimals can't be negative
+            return var.copy(compute_value=compute_val, number_of_decimals=num_decimals)
+        else:
+            return var.copy(compute_value=compute_val)

Orange/tests/test_normalize.py

@@ -159,14 +159,12 @@ def test_number_of_decimals(self):
         data = Table.from_list(Domain((foo,)), [[1], [2], [3]])
 
         normalized = Normalize()(data)
-        norm_foo = normalized.domain.attributes[0]
+        norm_foo: ContinuousVariable = normalized.domain.attributes[0]
 
-        self.assertEqual(norm_foo.number_of_decimals, 3)
-        self.assertEqual(norm_foo.format_str, "%g")
-        self.assertEqual(norm_foo.adjust_decimals, 2)
+        self.assertGreater(norm_foo.number_of_decimals, 0)
 
         for val1, val2 in zip(normalized[:, "Foo"],
-                              ["-1.22474", "0", "1.22474"]):
+                              ["-1.22474", "0.000", "1.22474"]):
             self.assertEqual(str(val1[0]), val2)