Python-Design-Patterns graph_search
graph_search Model
Python-Design-Patterns graph_search
# file: 'graph_search.py'
#!/usr/bin/env python
# -*- coding: utf-8 -*-
""
class GraphSearch:
"""Graph search emulation in python, from source
http://www.python.org/doc/essays/graphs/"""
def __init__(self, graph):
self.graph = graph
def find_path(self, start, end, path=None):
path = path or []
path.append(start)
if start == end:
return path
for node in self.graph.get(start, []):
if node not in path:
newpath = self.find_path(node, end, path[:])
if newpath:
return newpath
def find_all_path(self, start, end, path=None):
path = path or []
path.append(start)
if start == end:
return [path]
paths = []
for node in self.graph.get(start, []):
if node not in path:
newpaths = self.find_all_path(node, end, path[:])
paths.extend(newpaths)
return paths
def find_shortest_path(self, start, end, path=None):
path = path or []
path.append(start)
if start == end:
return path
shortest = None
for node in self.graph.get(start, []):
if node not in path:
newpath = self.find_shortest_path(node, end, path[:])
if newpath:
if not shortest or len(newpath) < len(shortest):
shortest = newpath
return shortest
# example of graph usage
graph = {'A': ['B', 'C'], 'B': ['C', 'D'], 'C': ['D'], 'D': ['C'], 'E': ['F'], 'F': ['C']}
# initialization of new graph search object
graph1 = GraphSearch(graph)
print(graph1.find_path('A', 'D'))
print(graph1.find_all_path('A', 'D'))
print(graph1.find_shortest_path('A', 'D'))
### OUTPUT ###
# ['A', 'B', 'C', 'D']
# [['A', 'B', 'C', 'D'], ['A', 'B', 'D'], ['A', 'C', 'D']]
# ['A', 'B', 'D']
graph_search.py
