Improve label_self_loops()

src/graph/stats/graph_parallel.cc

@@ -37,12 +37,13 @@ void do_label_parallel_edges(GraphInterface& gi, boost::any property,
                    edge_scalar_properties())(property);
 }
 
-void do_label_self_loops(GraphInterface& gi, boost::any property)
+void do_label_self_loops(GraphInterface& gi, boost::any property,
+                         bool mark_only)
 {
     GraphInterface::edge_index_map_t edge_index =
         any_cast<GraphInterface::edge_index_map_t>(gi.GetEdgeIndex());
     run_action<>()(gi, bind<void>(label_self_loops(), _1,
-                                  edge_index, _2),
+                                  edge_index, _2, mark_only),
                    edge_scalar_properties())(property);
 }
 

src/graph/stats/graph_parallel.hh

@@ -72,7 +72,7 @@ struct label_self_loops
 {
     template <class Graph, class EdgeIndexMap, class SelfMap>
     void operator()(const Graph& g, EdgeIndexMap edge_index,
-                    SelfMap self) const
+                    SelfMap self, bool mark_only) const
     {
         typedef typename graph_traits<Graph>::edge_descriptor edge_t;
 
@@ -89,7 +89,7 @@ struct label_self_loops
             for (tie(e, e_end) = out_edges(v, g); e != e_end; ++e)
             {
                 if (target(*e, g) == v)
-                    put(self, *e, n++);
+                    put(self, *e, mark_only ? 1 : n++);
                 else
                     put(self, *e, 0);
             }

src/graph_tool/stats/__init__.py

@@ -303,16 +303,21 @@ def remove_parallel_edges(g):
     remove_labeled_edges(g, eprop)
 
 
-def label_self_loops(g, eprop=None):
+def label_self_loops(g, mark_only=False, eprop=None):
     """Label edges which are self-loops, i.e, the source and target vertices are
-    the same. Self-loops are labeled with 1 and others with 0. If the `eprop`
-    parameter is given (a :class:`~graph_tool.PropertyMap`), the labelling is
-    stored there."""
+    the same. For each self-loop edge set :math:`SL`, the labelling starts from 0
+    to :math:`|SL|-1`. If `mark_only == True`, self-loops are labeled with 1
+    and others with 0. If the `eprop` parameter is given
+    (a :class:`~graph_tool.PropertyMap`), the labelling is stored there."""
 
-    if eprop == None:
-        eprop = g.new_edge_property("int32_t")
+    if eprop is None:
+        if mark_only:
+            eprop = g.new_edge_property("bool")
+        else:
+            eprop = g.new_edge_property("int32_t")
     libgraph_tool_stats.\
-          label_self_loops(g._Graph__graph, _prop("e", g, eprop))
+          label_self_loops(g._Graph__graph, _prop("e", g, eprop),
+                           mark_only)
     return eprop