transition(): Fix matrix transposition

src/graph/spectral/graph_transition.cc

@@ -37,7 +37,7 @@ void transition(GraphInterface& g, boost::any index, boost::any weight,
     if (!belongs<vertex_scalar_properties>()(index))
         throw ValueException("index vertex property must have a scalar value type");
 
-    typedef ConstantPropertyMap<double, GraphInterface::edge_t> weight_map_t;
+    typedef ConstantPropertyMap<size_t, GraphInterface::edge_t> weight_map_t;
     typedef mpl::push_back<edge_scalar_properties, weight_map_t>::type
         weight_props_t;
 
@@ -45,7 +45,7 @@ void transition(GraphInterface& g, boost::any index, boost::any weight,
         throw ValueException("weight edge property must have a scalar value type");
 
     if(weight.empty())
-        weight = weight_map_t(1.0);
+        weight = weight_map_t(1);
 
     multi_array_ref<double,1> data = get_array<double,1>(odata);
     multi_array_ref<int32_t,1> i = get_array<int32_t,1>(oi);

src/graph/spectral/graph_transition.hh

@@ -27,22 +27,21 @@ namespace graph_tool
 
 using namespace boost;
 
-template <class Graph, class Weight, class EdgeSelector>
+template <class Graph, class Weight>
 typename property_traits<Weight>::value_type
 sum_degree(Graph& g, typename graph_traits<Graph>::vertex_descriptor v,
-           Weight w, EdgeSelector)
+           const Weight& w)
 {
     typename property_traits<Weight>::value_type sum = 0;
-    typename EdgeSelector::type e, e_end;
-    for(tie(e, e_end) = EdgeSelector::get_edges(v, g); e != e_end; ++e)
-        sum += get(w, *e);
+    for(const auto& e : out_edges_range(v, g))
+        sum += get(w, e);
     return sum;
 }
 
-template <class Graph, class EdgeSelector>
-double
+template <class Graph>
+size_t
 sum_degree(Graph& g, typename graph_traits<Graph>::vertex_descriptor v,
-           ConstantPropertyMap<double, GraphInterface::edge_t> w, out_edge_iteratorS<Graph>)
+           const ConstantPropertyMap<size_t, GraphInterface::edge_t>&)
 {
     return out_degreeS()(v, g);
 }
@@ -58,12 +57,12 @@ struct get_transition
         int pos = 0;
         for (auto v: vertices_range(g))
         {
-            double k = sum_degree(g, v, weight, out_edge_iteratorS<Graph>());
+            auto k = sum_degree(g, v, weight);
             for (const auto& e: out_edges_range(v, g))
             {
-                data[pos] = weight[e] / k;
-                i[pos] = get(index, source(e, g));
-                j[pos] = get(index, target(e, g));
+                data[pos] = double(weight[e]) / k;
+                j[pos] = get(index, source(e, g));
+                i[pos] = get(index, target(e, g));
                 ++pos;
             }
         }

src/graph_tool/spectral/__init__.py

@@ -446,7 +446,7 @@ def transition(g, weight=None, index=None):
     .. note::
 
         For directed graphs the definition above means that the entry
-        :math:`T_{i,j}` corresponds to the directed edge :math:`j\to
+        :math:`T_{ij}` corresponds to the directed edge :math:`j\to
         i`. Although this is a typical definition in network and graph theory
         literature, many also use the transpose of this matrix.
 
@@ -500,9 +500,6 @@ def transition(g, weight=None, index=None):
     i = numpy.zeros(E, dtype="int32")
     j = numpy.zeros(E, dtype="int32")
 
-    if g.is_directed():
-        g = GraphView(g, reversed=True, skip_properties=True)
-
     libgraph_tool_spectral.transition(g._Graph__graph, _prop("v", g, index),
                                       _prop("e", g, weight), data, i, j)