Merge pull request #776 from igraph/feat/is_complete

feat: add is_complete()

CHANGELOG.md

@@ -1,5 +1,9 @@
 # igraph Python interface changelog
 
+### Added
+
+ - Added `Graph.is_complete()` to test if there is a connection between all distinct pair of vertices.
+
 ### Changed
 
  - Error messages issued when an attribute is not found now mention the name and type of that attribute.

src/_igraph/graphobject.c

@@ -548,6 +548,25 @@ PyObject *igraphmodule_Graph_is_simple(igraphmodule_GraphObject* self, PyObject*
 }
 
 
+/** \ingroup python_interface_graph
+ * \brief Checks whether an \c igraph.Graph object is a complete graph.
+ * \return \c True if the graph is complete, \c False otherwise.
+ * \sa igraph_is_complete
+ */
+PyObject *igraphmodule_Graph_is_complete(igraphmodule_GraphObject* self, PyObject* Py_UNUSED(_null)) {
+  igraph_bool_t res;
+
+  if (igraph_is_complete(&self->g, &res)) {
+    igraphmodule_handle_igraph_error();
+    return NULL;
+  }
+
+  if (res)
+    Py_RETURN_TRUE;
+  Py_RETURN_FALSE;
+}
+
+
 /** \ingroup python_interface_graph
  * \brief Determines whether a graph is a (directed or undirected) tree
  * \sa igraph_is_tree
@@ -13625,6 +13644,16 @@ struct PyMethodDef igraphmodule_Graph_methods[] = {
    "@return: C{True} if it is simple, C{False} otherwise.\n"
    "@rtype: boolean"},
 
+  /* interface to igraph_is_complete */
+  {"is_complete", (PyCFunction) igraphmodule_Graph_is_complete,
+   METH_NOARGS,
+   "is_complete()\n--\n\n"
+   "Checks whether the graph is complete, i.e. whether there is at least one\n"
+   "connection between all distinct pairs of vertices. In directed graphs,\n"
+   "ordered pairs are considered.\n\n"
+   "@return: C{True} if it is complete, C{False} otherwise.\n"
+   "@rtype: boolean"},
+
   /* interface to igraph_is_tree */
   {"is_tree", (PyCFunction) igraphmodule_Graph_is_tree,
    METH_VARARGS | METH_KEYWORDS,

src/igraph/adjacency.py

@@ -140,7 +140,7 @@ def _get_biadjacency(graph, types="type", *args, **kwds):
     bipartite adjacency matrix is an M{n} times M{m} matrix, where M{n} and
     M{m} are the number of vertices in the two vertex classes.
 
-    @param types: an igraph vector containing the vertex types, or an
+    @param types: a vector containing the vertex types, or an
       attribute name. Anything that evalulates to C{False} corresponds to
       vertices of the first kind, everything else to the second kind.
     @return: the bipartite adjacency matrix and two lists in a triplet. The

tests/test_bipartite.py

@@ -172,7 +172,9 @@ def testBipartiteProjection(self):
         g = Graph.Full_Bipartite(10, 5)
 
         g1, g2 = g.bipartite_projection()
+        self.assertTrue(g1.is_complete())
         self.assertTrue(g1.isomorphic(Graph.Full(10)))
+        self.assertTrue(g2.is_complete())
         self.assertTrue(g2.isomorphic(Graph.Full(5)))
         self.assertTrue(g.bipartite_projection(which=0).isomorphic(g1))
         self.assertTrue(g.bipartite_projection(which=1).isomorphic(g2))
@@ -183,15 +185,19 @@ def testBipartiteProjection(self):
         self.assertTrue(g.bipartite_projection_size() == (10, 45, 5, 10))
 
         g1, g2 = g.bipartite_projection(probe1=10)
+        self.assertTrue(g1.is_complete())
         self.assertTrue(g1.isomorphic(Graph.Full(5)))
+        self.assertTrue(g2.is_complete())
         self.assertTrue(g2.isomorphic(Graph.Full(10)))
         self.assertTrue(g.bipartite_projection(which=0).isomorphic(g2))
         self.assertTrue(g.bipartite_projection(which=1).isomorphic(g1))
         self.assertTrue(g.bipartite_projection(which=False).isomorphic(g2))
         self.assertTrue(g.bipartite_projection(which=True).isomorphic(g1))
 
         g1, g2 = g.bipartite_projection(multiplicity=False)
+        self.assertTrue(g1.is_complete())
         self.assertTrue(g1.isomorphic(Graph.Full(10)))
+        self.assertTrue(g2.is_complete())
         self.assertTrue(g2.isomorphic(Graph.Full(5)))
         self.assertTrue(g.bipartite_projection(which=0).isomorphic(g1))
         self.assertTrue(g.bipartite_projection(which=1).isomorphic(g2))

tests/test_generators.py

@@ -110,6 +110,7 @@ def testFull(self):
         g = Graph.Full(20, directed=True)
         el = g.get_edgelist()
         el.sort()
+        self.assertTrue(g.is_complete())
         self.assertTrue(
             g.get_edgelist() == [(x, y) for x in range(20) for y in range(20) if x != y]
         )