From 4a52a71956a8d46fcb7294ac71734504bb09bcc2 Mon Sep 17 00:00:00 2001 From: S. Solomon Darnell Date: Fri, 28 Mar 2025 21:52:21 -0500 Subject: two version of R2R are here --- .../networkx/generators/stochastic.py | 54 ++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 .venv/lib/python3.12/site-packages/networkx/generators/stochastic.py (limited to '.venv/lib/python3.12/site-packages/networkx/generators/stochastic.py') diff --git a/.venv/lib/python3.12/site-packages/networkx/generators/stochastic.py b/.venv/lib/python3.12/site-packages/networkx/generators/stochastic.py new file mode 100644 index 00000000..f53e2315 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/generators/stochastic.py @@ -0,0 +1,54 @@ +"""Functions for generating stochastic graphs from a given weighted directed +graph. + +""" + +import networkx as nx +from networkx.classes import DiGraph, MultiDiGraph +from networkx.utils import not_implemented_for + +__all__ = ["stochastic_graph"] + + +@not_implemented_for("undirected") +@nx._dispatchable( + edge_attrs="weight", mutates_input={"not copy": 1}, returns_graph=True +) +def stochastic_graph(G, copy=True, weight="weight"): + """Returns a right-stochastic representation of directed graph `G`. + + A right-stochastic graph is a weighted digraph in which for each + node, the sum of the weights of all the out-edges of that node is + 1. If the graph is already weighted (for example, via a 'weight' + edge attribute), the reweighting takes that into account. + + Parameters + ---------- + G : directed graph + A :class:`~networkx.DiGraph` or :class:`~networkx.MultiDiGraph`. + + copy : boolean, optional + If this is True, then this function returns a new graph with + the stochastic reweighting. Otherwise, the original graph is + modified in-place (and also returned, for convenience). + + weight : edge attribute key (optional, default='weight') + Edge attribute key used for reading the existing weight and + setting the new weight. If no attribute with this key is found + for an edge, then the edge weight is assumed to be 1. If an edge + has a weight, it must be a positive number. + + """ + if copy: + G = MultiDiGraph(G) if G.is_multigraph() else DiGraph(G) + # There is a tradeoff here: the dictionary of node degrees may + # require a lot of memory, whereas making a call to `G.out_degree` + # inside the loop may be costly in computation time. + degree = dict(G.out_degree(weight=weight)) + for u, v, d in G.edges(data=True): + if degree[u] == 0: + d[weight] = 0 + else: + d[weight] = d.get(weight, 1) / degree[u] + nx._clear_cache(G) + return G -- cgit v1.2.3