Correct documentation for purge_vertices()/edges()

doc/graph_tool.rst

@@ -151,10 +151,9 @@
     .. warning::
 
       The purge functions below irreversibly remove the filtered
-      vertices or edges from the graph, and return it to an
-      unfiltered state. Note that, contrary to the functions above,
-      these are :math:`O(V)` and :math:`O(E)` operations,
-      respectively.
+      vertices or edges from the graph. Note that, contrary to the
+      functions above, these are :math:`O(V)` and :math:`O(E)`
+      operations, respectively.
 
     .. automethod:: purge_vertices
     .. automethod:: purge_edges

src/graph_tool/__init__.py

@@ -2198,9 +2198,8 @@ class Graph(object):
         self.__filter_state["edge_filter"] = (None, False)
 
     def purge_vertices(self, in_place=False):
-        """Remove all vertices of the graph which are currently being filtered
-        out, and return it to the unfiltered state. This operation is not
-        reversible.
+        """Remove all vertices of the graph which are currently being filtered out. This
+        operation is not reversible.
 
         If the option ``in_place == True`` is given, the algorithm will remove
         the filtered vertices and re-index all property maps which are tied with
@@ -2213,6 +2212,12 @@ class Graph(object):
         with an :math:`O(N + E)` complexity. This is the default behaviour if no
         option is given.
 
+        .. note :
+
+           The graph will remain in a filtered state after this operation, since
+           there might be edge filters present. To return the graph to an
+           unfiltered state, use :meth:`~graph_tool.Graph.clear_filters`.
+
         """
         if in_place:
             old_indexes = self.vertex_index.copy("int64_t")
@@ -2250,8 +2255,16 @@ class Graph(object):
                 self.set_edge_filter(efilt[0], efilt[1])
 
     def purge_edges(self):
-        """Remove all edges of the graph which are currently being filtered out,
-        and return it to the unfiltered state. This operation is not reversible."""
+        """Remove all edges of the graph which are currently being filtered out. This
+        operation is not reversible.
+
+        .. note :
+
+           The graph will remain in a filtered state after this operation, since
+           there might be vertex filters present. To return the graph to an
+           unfiltered state, use :meth:`~graph_tool.Graph.clear_filters`.
+
+        """
         self.__graph.PurgeEdges()
         self.set_edge_filter(None)