/usr/lib/python3/dist-packages/pygraph/algorithms/traversal.py is in python3-pygraph 1.8.2-6.
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#
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"""
Traversal algorithms.
@sort: traversal
"""
# Minimal spanning tree
def traversal(graph, node, order):
"""
Graph traversal iterator.
@type graph: graph, digraph
@param graph: Graph.
@type node: node
@param node: Node.
@type order: string
@param order: traversal ordering. Possible values are:
2. 'pre' - Preordering (default)
1. 'post' - Postordering
@rtype: iterator
@return: Traversal iterator.
"""
visited = {}
if (order == 'pre'):
pre = 1
post = 0
elif (order == 'post'):
pre = 0
post = 1
for each in _dfs(graph, visited, node, pre, post):
yield each
def _dfs(graph, visited, node, pre, post):
"""
Depth-first search subfunction for traversals.
@type graph: graph, digraph
@param graph: Graph.
@type visited: dictionary
@param visited: List of nodes (visited nodes are marked non-zero).
@type node: node
@param node: Node to be explored by DFS.
"""
visited[node] = 1
if (pre): yield node
# Explore recursively the connected component
for each in graph[node]:
if (each not in visited):
for other in _dfs(graph, visited, each, pre, post):
yield other
if (post): yield node
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