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graph_search.py
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86 lines (72 loc) · 2.4 KB
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#!/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):
self.start = start
self.end = end
self.path = path if path else []
self.path += [self.start]
if self.start == self.end:
return self.path
if self.start not in self.graph:
return None
for node in self.graph[self.start]:
if node not in self.path:
newpath = self.find_path(node, self.end, self.path)
if newpath:
return newpath
return None
def find_all_path(self, start, end, path=None):
self.start = start
self.end = end
_path = path if path else []
_path += [self.start]
if self.start == self.end:
return [_path]
if self.start not in self.graph:
return []
paths = []
for node in self.graph[self.start]:
if node not in _path:
newpaths = self.find_all_path(node, self.end, _path[:])
for newpath in newpaths:
paths.append(newpath)
return paths
def find_shortest_path(self, start, end, path=None):
self.start = start
self.end = end
_path = path if path else []
_path += [self.start]
if self.start == self.end:
return _path
if self.start not in self.graph:
return None
shortest = None
for node in self.graph[self.start]:
if node not in _path:
newpath = self.find_shortest_path(node, self.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']