--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/graph/traversal.py Thu Nov 27 23:41:08 2008 +0000
@@ -0,0 +1,81 @@
+# Copyright (c) 2007-2008 Pedro Matiello <pmatiello@gmail.com>
+#
+# Permission is hereby granted, free of charge, to any person
+# obtaining a copy of this software and associated documentation
+# files (the "Software"), to deal in the Software without
+# restriction, including without limitation the rights to use,
+# copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following
+# conditions:
+
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+# OTHER DEALINGS IN THE SOFTWARE.
+
+
+"""
+Traversal algorithms for python-graph.
+
+@sort: traversal
+"""
+
+
+# Minimal spanning tree
+
+def traversal(graph, node, order):
+ """
+ Graph traversal iterator.
+
+ @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):
+ """
+ Depht-first search subfunction for traversals.
+
+ @type graph: graph
+ @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