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