Merge pull request #270 from higra/fix_empty_bipartite_graph_matching

Fix bipartite graph matching with empty graph

higra/algo/bipartite_graph.py

@@ -129,12 +129,22 @@ def bipartite_graph_matching(graph, edge_weights):
             targets = graph[1]
             num_vertices = graph[2]
             num_edges = len(sources)
+
+            if len(targets) != num_edges:
+                raise ValueError("sources and targets must have the same length")
+
         except Exception as e:
             raise TypeError("graph must be an undirected graph or a tuple (sources, targets, num_vertices)", e)
 
+    if len(edge_weights) != num_edges:
+        raise ValueError("edge_weights must have the same length as the number of edges of the graph")
+
     if not check:
         raise ValueError("graph must be bipartite")
 
+    if num_edges == 0:
+        return np.array([], dtype=np.int64)
+
     # if edge weights dtype is floating point, emit a warning
     if np.issubdtype(edge_weights.dtype, np.floating):
         print("Warning: possible loss of precision, edge weights are casted to int64 for bipartite graph matching")

test/python/test_algo/test_bipartite_graph.py

@@ -58,6 +58,13 @@ def test_is_bipartite_graph_false(self):
         self.assertFalse(ans)
         self.assertTrue(len(color) == 0)
 
+    def test_bipartite_graph_matching_empty(self):
+        g = hg.UndirectedGraph(6)
+        weights = np.array([])
+
+        edges = hg.bipartite_graph_matching(g, weights)
+        self.assertTrue(len(edges) == 0)
+
     def test_bipartite_graph_matching(self):
         g = hg.UndirectedGraph(6)
         g.add_edges(np.array([0, 0, 1, 1, 2, 1]), np.array([3, 4, 3, 5, 5, 4]))

test/python/test_image/test_graph_image.py

@@ -101,6 +101,17 @@ def test_get_nd_regular_graph(self):
 
         self.assertTrue(ref_edges == res_edges)
 
+    def test_match_pixels_image_2d_empty(self):
+        im1 = np.asarray([[1, 0, 0, 0],
+                          [0, 0, 0, 0]])
+        im2 = np.asarray([[0, 0, 0, 1],
+                          [0, 0, 0, 0]])
+
+        sources, targets = hg.match_pixels_image_2d(im1, im2, 1.3, "absolute")
+
+        self.assertTrue(len(sources) == 0)
+        self.assertTrue(len(targets) == 0)
+
     def test_match_pixels_image_2d(self):
         im1 = np.asarray([[1, 0, 0, 1],
                           [0, 0, 0, 1]])

tools/azure-pipelines-linux-gcc.yml

@@ -39,7 +39,7 @@ jobs:
       - script: |
           conda config --set always_yes yes --set changeps1 no
           conda update -q conda
-          conda install tbb-devel==2019.9 scikit-learn==1.0.1 -c conda-forge
+          conda install tbb-devel==2019.9 scikit-learn -c conda-forge
         displayName: Install python packages
 
       - script: |

tools/azure-pipelines-mac.yml

@@ -31,7 +31,7 @@ jobs:
       - script: |
           conda config --set always_yes yes --set changeps1 no
           conda update -q conda
-          conda install cmake tbb-devel==2019.9 scikit-learn==1.0.1 -c conda-forge
+          conda install cmake tbb-devel==2019.9 scikit-learn -c conda-forge
         displayName: Install python packages
 
       - script: |