Raising exception when overlap_frac <= 0

Author: lucasimi

src/tdamapper/cover.py

@@ -303,10 +303,14 @@ def fit(self, X):
         else:
             self.__overlap_frac = self.overlap_frac
         self.__n_intervals = self.n_intervals
-        if (self.__overlap_frac <= 0.0) or (self.__overlap_frac > 0.5):
+        if self.__overlap_frac <= 0.0:
+            raise ValueError(
+                'The parameter overlap_frac is expected to be '
+                '> 0.0'
+            )
+        if self.__overlap_frac > 0.5:
             warn_user(
-                'The parameter overlap_frac is expected within range '
-                '(0.0, 0.5]'
+                'The parameter overlap_frac is expected to be <= 0.5'
             )
         self.__min, self.__max, self.__delta = self._get_bounds(X)
         radius = 1.0 / (2.0 - 2.0 * self.__overlap_frac)

tests/test_unit_core.py

@@ -160,6 +160,14 @@ def test_cubical_line(self):
         g = mp.fit_transform(data, data)
         self.assertEqual(4, len(g.nodes))
 
+    def test_cubical_no_overlap(self):
+        data = np.array([[0.0], [1.0], [2.0]])
+        cover = StandardCubicalCover(n_intervals=2, overlap_frac=0)
+        clustering = TrivialClustering()
+        mp = MapperAlgorithm(cover, clustering)
+        with self.assertRaises(ValueError):
+            mp.fit_transform(data, data)
+
     def test_mock_connected_components(self):
         data = [0, 1, 2, 3]