diff env/lib/python3.9/site-packages/networkx/algorithms/mis.py @ 0:4f3585e2f14b draft default tip

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.9/site-packages/networkx/algorithms/mis.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,77 @@
+"""
+Algorithm to find a maximal (not maximum) independent set.
+
+"""
+import networkx as nx
+from networkx.utils import not_implemented_for
+from networkx.utils import py_random_state
+
+__all__ = ["maximal_independent_set"]
+
+
+@py_random_state(2)
+@not_implemented_for("directed")
+def maximal_independent_set(G, nodes=None, seed=None):
+    """Returns a random maximal independent set guaranteed to contain
+    a given set of nodes.
+
+    An independent set is a set of nodes such that the subgraph
+    of G induced by these nodes contains no edges. A maximal
+    independent set is an independent set such that it is not possible
+    to add a new node and still get an independent set.
+
+    Parameters
+    ----------
+    G : NetworkX graph
+
+    nodes : list or iterable
+       Nodes that must be part of the independent set. This set of nodes
+       must be independent.
+
+    seed : integer, random_state, or None (default)
+        Indicator of random number generation state.
+        See :ref:`Randomness<randomness>`.
+
+    Returns
+    -------
+    indep_nodes : list
+       List of nodes that are part of a maximal independent set.
+
+    Raises
+    ------
+    NetworkXUnfeasible
+       If the nodes in the provided list are not part of the graph or
+       do not form an independent set, an exception is raised.
+
+    NetworkXNotImplemented
+        If `G` is directed.
+
+    Examples
+    --------
+    >>> G = nx.path_graph(5)
+    >>> nx.maximal_independent_set(G)  # doctest: +SKIP
+    [4, 0, 2]
+    >>> nx.maximal_independent_set(G, [1])  # doctest: +SKIP
+    [1, 3]
+
+    Notes
+    -----
+    This algorithm does not solve the maximum independent set problem.
+
+    """
+    if not nodes:
+        nodes = {seed.choice(list(G))}
+    else:
+        nodes = set(nodes)
+    if not nodes.issubset(G):
+        raise nx.NetworkXUnfeasible(f"{nodes} is not a subset of the nodes of G")
+    neighbors = set.union(*[set(G.adj[v]) for v in nodes])
+    if set.intersection(neighbors, nodes):
+        raise nx.NetworkXUnfeasible(f"{nodes} is not an independent set of G")
+    indep_nodes = list(nodes)
+    available_nodes = set(G.nodes()).difference(neighbors.union(nodes))
+    while available_nodes:
+        node = seed.choice(list(available_nodes))
+        indep_nodes.append(node)
+        available_nodes.difference_update(list(G.adj[node]) + [node])
+    return indep_nodes