本文整理汇总了Python中sage.graphs.digraph.DiGraph.edge_iterator方法的典型用法代码示例。如果您正苦于以下问题：Python DiGraph.edge_iterator方法的具体用法？Python DiGraph.edge_iterator怎么用？Python DiGraph.edge_iterator使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类sage.graphs.digraph.DiGraph的用法示例。
在下文中一共展示了DiGraph.edge_iterator方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Python代码示例。
示例1: is_partial_cube
# 需要导入模块: from sage.graphs.digraph import DiGraph [as 别名]
# 或者: from sage.graphs.digraph.DiGraph import edge_iterator [as 别名]
#.........这里部分代码省略.........
# - contracted: contracted graph at current stage of algorithm
# - unionfind: union find data structure representing known edge equivalences
# - available: limit on number of remaining available labels
from sage.graphs.digraph import DiGraph
from sage.graphs.graph import Graph
from sage.sets.disjoint_set import DisjointSet
contracted = DiGraph({v: {w: (v, w) for w in G[v]} for v in G})
unionfind = DisjointSet(contracted.edges(labels = False))
available = n-1
# Main contraction loop in place of the original algorithm's recursion
while contracted.order() > 1:
# Find max degree vertex in contracted, and update label limit
deg, root = max((contracted.out_degree(v), v) for v in contracted)
if deg > available:
return fail
available -= deg
# Set up bitvectors on vertices
bitvec = {v:0 for v in contracted}
neighbors = {}
for i, neighbor in enumerate(contracted[root]):
bitvec[neighbor] = 1 << i
neighbors[1 << i] = neighbor
# Breadth first search to propagate bitvectors to the rest of the graph
for level in breadth_first_level_search(contracted, root):
for v in level:
for w in level[v]:
bitvec[w] |= bitvec[v]
# Make graph of labeled edges and union them together
labeled = Graph([contracted.vertices(), []])
for v, w in contracted.edge_iterator(labels = False):
diff = bitvec[v]^bitvec[w]
if not diff or bitvec[w] &~ bitvec[v] == 0:
continue # zero edge or wrong direction
if diff not in neighbors:
return fail
neighbor = neighbors[diff]
unionfind.union(contracted.edge_label(v, w),
contracted.edge_label(root, neighbor))
unionfind.union(contracted.edge_label(w, v),
contracted.edge_label(neighbor, root))
labeled.add_edge(v, w)
# Map vertices to components of labeled-edge graph
component = {}
for i, SCC in enumerate(labeled.connected_components()):
for v in SCC:
component[v] = i
# generate new compressed subgraph
newgraph = DiGraph()
for v, w, t in contracted.edge_iterator():
if bitvec[v] == bitvec[w]:
vi = component[v]
wi = component[w]
if vi == wi:
return fail
if newgraph.has_edge(vi, wi):
unionfind.union(newgraph.edge_label(vi, wi), t)
else:
newgraph.add_edge(vi, wi, t)
contracted = newgraph