| :mod:`altgraph.GraphUtil` --- Utility functions |
| ================================================ |
| |
| .. module:: altgraph.GraphUtil |
| :synopsis: Utility functions |
| |
| The module :mod:`altgraph.GraphUtil` performs a number of more |
| or less useful utility functions. |
| |
| .. function:: generate_random_graph(node_num, edge_num[, self_loops[, multi_edges]) |
| |
| Generates and returns a :class:`Graph <altgraph.Graph.Graph>` instance |
| with *node_num* nodes randomly connected by *edge_num* edges. |
| |
| When *self_loops* is present and True there can be edges that point from |
| a node to itself. |
| |
| When *multi_edge* is present and True there can be duplicate edges. |
| |
| This method raises :class:`GraphError <altgraph.GraphError` when |
| a graph with the requested configuration cannot be created. |
| |
| .. function:: generate_scale_free_graph(steps, growth_num[, self_loops[, multi_edges]]) |
| |
| Generates and returns a :py:class:`~altgraph.Graph.Graph` instance that |
| will have *steps*growth_n um* nodes and a scale free (powerlaw) |
| connectivity. |
| |
| Starting with a fully connected graph with *growth_num* nodes |
| at every step *growth_num* nodes are added to the graph and are connected |
| to existing nodes with a probability proportional to the degree of these |
| existing nodes. |
| |
| .. warning:: The current implementation is basically untested, although |
| code inspection seems to indicate an implementation that is consistent |
| with the description at |
| `Wolfram MathWorld <http://mathworld.wolfram.com/Scale-FreeNetwork.html>`_ |
| |
| .. function:: filter_stack(graph, head, filters) |
| |
| Perform a depth-first oder walk of the graph starting at *head* and |
| apply all filter functions in *filters* on the node data of the nodes |
| found. |
| |
| Returns (*visited*, *removes*, *orphans*), where |
| |
| * *visited*: the set of visited nodes |
| |
| * *removes*: the list of nodes where the node data doesn't match |
| all *filters*. |
| |
| * *orphans*: list of tuples (*last_good*, *node*), where |
| node is not in *removes* and one of the nodes that is connected |
| by an incoming edge is in *removes*. *Last_good* is the |
| closest upstream node that is not in *removes*. |
