Ticket #12933: trac_12933.patch

sage/graphs/digraph.py

@@ -2960 +2960 @@
 
         if keep_labels:
             g = DiGraph(multiedges=True, loops=True)
-            g.add_vertices(scc_set)
-            g.add_edges( set((scc_set[d[u]], scc_set[d[v]], label) for (u,v,label) in self.edges() ) )
+            g.add_vertices(range(len(scc)))
+
+            g.add_edges( set((d[u], d[v], label) for (u,v,label) in self.edges() ) )
+            g.relabel(scc_set, inplace = True)
+
         else:
             g = DiGraph(multiedges=False, loops=False)
-            g.add_vertices(scc_set)
-            g.add_edges( (scc_set[d[u]], scc_set[d[v]]) for u,v in self.edges(labels=False) )
+            g.add_vertices(range(len(scc)))
+
+            for u,v in self.edges(labels=False):
+                g.add_edge(d[u], d[v])
+
+            g.relabel(scc_set, inplace = True)
 
         return g
 
@@ -2974 +2981 @@
         Returns whether the current ``DiGraph`` is strongly connected.
 
         EXAMPLE:
-        
+
         The circuit is obviously strongly connected ::
 
             sage: g = digraphs.Circuit(5)

sage/graphs/graph.py

@@ -2506 +2506 @@
         from sage.graphs.chrompoly import chromatic_polynomial
         return chromatic_polynomial(self)
 
-    def chromatic_number(self, algorithm="DLX"):
+    def chromatic_number(self, algorithm="DLX", verbose = 0):
         r"""
         Returns the minimal number of colors needed to color the vertices
         of the graph `G`.
@@ -2533 +2533 @@
             (see the :mod:`MILP module <sage.numerical.mip>`, or Sage's tutorial
             on Linear Programming).
 
+        - ``verbose`` -- integer (default: ``0``). Sets the level of verbosity
+          for the MILP algorithm. Its default value is 0, which means *quiet*.
+
         .. SEEALSO::
 
             For more functions related to graph coloring, see the
@@ -2564 +2567 @@
         # package: choose any of GLPK or CBC.
         elif algorithm == "MILP":
             from sage.graphs.graph_coloring import vertex_coloring
-            return vertex_coloring(self, value_only=True)
+            return vertex_coloring(self, value_only=True, verbose = verbose)
         # another algorithm with bad performance; only good for small graphs
         elif algorithm == "CP":
             f = self.chromatic_polynomial()
@@ -2575 +2578 @@
         else:
             raise ValueError("The 'algorithm' keyword must be set to either 'DLX', 'MILP' or 'CP'.")
 
-    def coloring(self, algorithm="DLX", hex_colors=False):
+    def coloring(self, algorithm="DLX", hex_colors=False, verbose = 0):
         r"""
         Returns the first (optimal) proper vertex-coloring found.
         
@@ -2595 +2598 @@
         - ``hex_colors`` -- (default: ``False``) if ``True``, return a
           dictionary which can easily be used for plotting.
 
+        - ``verbose`` -- integer (default: ``0``). Sets the level of verbosity
+          for the MILP algorithm. Its default value is 0, which means *quiet*.
+
         .. SEEALSO::
 
             For more functions related to graph coloring, see the
@@ -2631 +2637 @@
         """
         if algorithm == "MILP":
             from sage.graphs.graph_coloring import vertex_coloring
-            return vertex_coloring(self, hex_colors=hex_colors)
+            return vertex_coloring(self, hex_colors=hex_colors, verbose = verbose)
         elif algorithm == "DLX":
             from sage.graphs.graph_coloring import first_coloring
             return first_coloring(self, hex_colors=hex_colors)