61 lines
1.9 KiB
Python
61 lines
1.9 KiB
Python
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import networkx as nx
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__all__ = ["s_metric"]
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@nx._dispatch
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def s_metric(G, **kwargs):
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"""Returns the s-metric [1]_ of graph.
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The s-metric is defined as the sum of the products ``deg(u) * deg(v)``
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for every edge ``(u, v)`` in `G`.
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Parameters
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----------
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G : graph
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The graph used to compute the s-metric.
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normalized : bool (optional)
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Normalize the value.
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.. deprecated:: 3.2
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The `normalized` keyword argument is deprecated and will be removed
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in the future
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Returns
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-------
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s : float
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The s-metric of the graph.
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References
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----------
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.. [1] Lun Li, David Alderson, John C. Doyle, and Walter Willinger,
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Towards a Theory of Scale-Free Graphs:
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Definition, Properties, and Implications (Extended Version), 2005.
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https://arxiv.org/abs/cond-mat/0501169
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"""
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# NOTE: This entire code block + the **kwargs in the signature can all be
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# removed when the deprecation expires.
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# Normalized is always False, since all `normalized=True` did was raise
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# a NotImplementedError
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if kwargs:
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# Warn for `normalize`, raise for any other kwarg
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if "normalized" in kwargs:
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import warnings
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warnings.warn(
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"\n\nThe `normalized` keyword is deprecated and will be removed\n"
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"in the future. To silence this warning, remove `normalized`\n"
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"when calling `s_metric`.\n\n"
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"The value of `normalized` is ignored.",
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DeprecationWarning,
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stacklevel=3,
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)
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else:
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# Typical raising behavior for Python when kwarg not recognized
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raise TypeError(
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f"s_metric got an unexpected keyword argument '{list(kwargs.keys())[0]}'"
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)
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return float(sum(G.degree(u) * G.degree(v) for (u, v) in G.edges()))
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