Fix parition_asymmetry Uylings to not throw for bifurcations with lea…

…ves (#1001)

CHANGELOG.rst

@@ -3,6 +3,15 @@ Changelog
 
 Version 3.2.0
 -------------
+
+- Fix ``neurom.features.bifurcation.partition_asymmetry`` Uylings variant to not throw
+  for bifurcations with leaves.
+- Fix ``neurom.features.neurite.principal_direction_extents`` to remove duplicate points
+  when calculated.
+- Add ``neurom.features.morphology.volume_density`` feature so that it is calculated
+  correctly when the entire morphology is taken into account instead of summing the per
+  neurite volume densities.
+- Add support for py39 and py310 testing.
 - Fix ``neurom.features.morphology.sholl_frequency`` to return an empty list when a
   neurite_type that is not present in the morphology is specified.
 - Fix ``neurom.features.morphology.trunk_origin_radii`` to warn and use only the root

neurom/features/bifurcation.py

@@ -115,12 +115,13 @@ def partition_asymmetry(bif_point, uylings=False):
 
     n = float(sum(1 for _ in bif_point.children[0].ipreorder()))
     m = float(sum(1 for _ in bif_point.children[1].ipreorder()))
-    c = 0
-    if uylings:
-        c = 2
-        if n + m <= c:
-            raise NeuroMError('Partition asymmetry cant be calculated by Uylings because the sum of'
-                              'terminal tips is less than 2.')
+
+    if n == m == 1:
+        # By definition the asymmetry A(1, 1) is zero
+        return 0.0
+
+    c = 2.0 if uylings else 0.0
+
     return abs(n - m) / abs(n + m - c)
 
 

tests/features/test_bifurcation.py

@@ -80,8 +80,7 @@ def test_partition_asymmetry():
     assert bf.partition_asymmetry(root) == 0.5
     assert bf.partition_asymmetry(root.children[0]) == 0.0
     assert bf.partition_asymmetry(root, True) == 1.0
-    with pytest.raises(NeuroMError, match='Uylings'):
-        bf.partition_asymmetry(root.children[0], True)
+    assert bf.partition_asymmetry(root.children[0], True) == 0.0
 
     leaf = root.children[0].children[0]
     assert_raises(NeuroMError, bf.partition_asymmetry, leaf)