## Mercurial > repos > shellac > sam_consensus_v3

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

Find changesets by keywords (author, files, the commit message), revision
number or hash, or revset expression.

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

author | shellac |
---|---|

date | Mon, 22 Mar 2021 18:12:50 +0000 |

parents | |

children |

line wrap: on

line source

"""Algorithms to calculate reciprocity in a directed graph.""" from networkx import NetworkXError from ..utils import not_implemented_for __all__ = ["reciprocity", "overall_reciprocity"] @not_implemented_for("undirected", "multigraph") def reciprocity(G, nodes=None): r"""Compute the reciprocity in a directed graph. The reciprocity of a directed graph is defined as the ratio of the number of edges pointing in both directions to the total number of edges in the graph. Formally, $r = |{(u,v) \in G|(v,u) \in G}| / |{(u,v) \in G}|$. The reciprocity of a single node u is defined similarly, it is the ratio of the number of edges in both directions to the total number of edges attached to node u. Parameters ---------- G : graph A networkx directed graph nodes : container of nodes, optional (default=whole graph) Compute reciprocity for nodes in this container. Returns ------- out : dictionary Reciprocity keyed by node label. Notes ----- The reciprocity is not defined for isolated nodes. In such cases this function will return None. """ # If `nodes` is not specified, calculate the reciprocity of the graph. if nodes is None: return overall_reciprocity(G) # If `nodes` represents a single node in the graph, return only its # reciprocity. if nodes in G: reciprocity = next(_reciprocity_iter(G, nodes))[1] if reciprocity is None: raise NetworkXError("Not defined for isolated nodes.") else: return reciprocity # Otherwise, `nodes` represents an iterable of nodes, so return a # dictionary mapping node to its reciprocity. return dict(_reciprocity_iter(G, nodes)) def _reciprocity_iter(G, nodes): """ Return an iterator of (node, reciprocity). """ n = G.nbunch_iter(nodes) for node in n: pred = set(G.predecessors(node)) succ = set(G.successors(node)) overlap = pred & succ n_total = len(pred) + len(succ) # Reciprocity is not defined for isolated nodes. # Return None. if n_total == 0: yield (node, None) else: reciprocity = 2.0 * float(len(overlap)) / float(n_total) yield (node, reciprocity) @not_implemented_for("undirected", "multigraph") def overall_reciprocity(G): """Compute the reciprocity for the whole graph. See the doc of reciprocity for the definition. Parameters ---------- G : graph A networkx graph """ n_all_edge = G.number_of_edges() n_overlap_edge = (n_all_edge - G.to_undirected().number_of_edges()) * 2 if n_all_edge == 0: raise NetworkXError("Not defined for empty graphs") return float(n_overlap_edge) / float(n_all_edge)