Support boolean views on numeric dtypes

scikit-image · Sep 19, 2019 · b2bb144 · b2bb144
1 parent 3d565fd
commit b2bb144
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Showing 3 changed files with 25 additions and 8 deletions.
diff --git a/skimage/morphology/_close_objects_cy.pyx b/skimage/morphology/_close_objects_cy.pyx
@@ -60,7 +60,7 @@ def _remove_close_objects(
     try:
         for i in range(indices.shape[0]):
             index_i = indices[i]
-            if image[index_i] != 1:
+            if image[index_i] == 0:
                 continue
 
             in_range = kdtree.query_ball_point(
@@ -69,7 +69,7 @@ def _remove_close_objects(
             for j in in_range:
                 index_j = indices[j]
                 if (
-                    image[index_j] == 1
+                    image[index_j] > 0
                     and labels[index_i] != labels[index_j]
                 ):
                     _remove_object(
@@ -121,6 +121,6 @@ cdef inline void _remove_object(
                 continue
             # The algorithm might cross the image edge when two objects are
             # neighbors in the raveled view -> check label to avoid that
-            if image[neighbor] == 1 and labels[neighbor] == label:
+            if image[neighbor] > 0 and labels[neighbor] == label:
                 queue_push(queue_ptr, &neighbor)
                 image[neighbor] = 0
diff --git a/skimage/morphology/misc.py b/skimage/morphology/misc.py
@@ -308,14 +308,14 @@ def remove_close_objects(
     ...     image.view(bool), minimal_distance=3, priority=image
     ... )
     >>> result.view(np.uint8)
-    array([[1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1],
-           [1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1],
-           [0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
+    array([[8, 0, 0, 0, 0, 0, 0, 0, 0, 9, 9],
+           [8, 8, 8, 0, 0, 0, 0, 0, 0, 9, 9],
+           [0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0],
            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
-           [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+           [2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
            [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
-           [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1]], dtype=uint8)
+           [0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 7]], dtype=uint8)
     """
     if not np.can_cast(image, bool, casting="same_kind"):
         # Cython doesn't support boolean memoryviews yet

diff --git a/skimage/morphology/tests/test_misc.py b/skimage/morphology/tests/test_misc.py
@@ -280,3 +280,20 @@ def test_priority(self):
         )
         desired = np.array([[0, 0, 0], [0, 0, 0], [1, 0, 0]], dtype=bool)
         assert_array_equal(result, desired)
+
+    @pytest.mark.parametrize("dtype", [np.uint8, np.int8])
+    def test_view_on_byte_sized(self, dtype):
+        """Test behavior if image is a view on 1 byte sized numeric dtypes."""
+        image = np.array([-2, 0, 2], dtype=dtype)
+
+        # When using a view, object values don't change
+        result_view = remove_close_objects(image.view(bool), 2)
+        desired_view = np.array([-2, 0, 0], dtype=dtype)
+        assert result_view.dtype is np.dtype(bool)
+        assert_array_equal(result_view.view(dtype), desired_view)
+
+        # When using astype, the object values > 0 are replaced with 1
+        result_astype = remove_close_objects(image.astype(bool), 2)
+        desired_astype = np.array([1, 0, 0], dtype=np.uint8)
+        assert_array_equal(result_astype, result_view)
+        assert_array_equal(result_astype.view(np.uint8), desired_astype)