Add support for looping edges in Chords element (#2583)

holoviz · Apr 19, 2018 · 97bc1dd · 97bc1dd
1 parent 876ddf9
commit 97bc1dd
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Showing 2 changed files with 14 additions and 4 deletions.
diff --git a/holoviews/element/graphs.py b/holoviews/element/graphs.py
@@ -581,7 +581,7 @@ def _process(self, element, key=None):
             matrix[s, t] += v
 
         # Compute weighted angular slice for each connection
-        weights_of_areas = (matrix.sum(axis=0) + matrix.sum(axis=1)) - matrix.diagonal()
+        weights_of_areas = (matrix.sum(axis=0) + matrix.sum(axis=1))
         areas_in_radians = (weights_of_areas / weights_of_areas.sum()) * (2 * np.pi)
 
         # We add a zero in the begging for the cumulative sum
@@ -608,9 +608,11 @@ def _process(self, element, key=None):
         empty = np.array([[np.NaN, np.NaN]])
         paths = []
         for i in range(len(element)):
-            src_area, tgt_area = all_areas[src_idx[i]], all_areas[tgt_idx[i]]
+            sidx, tidx = src_idx[i], tgt_idx[i]
+            src_area, tgt_area = all_areas[sidx], all_areas[tidx]
+            n_conns = matrix[sidx, tidx]
             subpaths = []
-            for _ in range(int(values[i])):
+            for _ in range(int(n_conns)):
                 if not src_area or not tgt_area:
                     continue
                 x0, y0 = src_area.pop()
@@ -625,7 +627,7 @@ def _process(self, element, key=None):
             if subpaths:
                 paths.append(np.concatenate(subpaths))
             else:
-                paths.append(np.array([]))
+                paths.append(np.empty((0, 2)))
 
         # Construct Chord element from components
         if nodes_el:

diff --git a/tests/element/testgraphelement.py b/tests/element/testgraphelement.py
@@ -155,6 +155,14 @@ def test_chord_constructor_with_vdims(self):
         self.assertEqual(chord.nodes, Nodes(nodes))
         self.assertEqual(chord.array(), np.array(self.simplices))
 
+    def test_chord_constructor_self_reference(self):
+        chord = Chord([('A', 'B', 2), ('B', 'A', 3), ('A', 'A', 2)])
+        nodes = np.array(
+            [[-0.5, 0.866025, 0],
+             [0.5, -0.866025, 1]]
+        ) 
+        self.assertEqual(chord.nodes, Nodes(nodes))
+
 
 
 class TriMeshTests(ComparisonTestCase):