Python Data Structure Graph implementation method, python data structure implementation

Python Data Structure Graph implementation method, python data structure implementation

This article describes how to implement a graph of the python data structure. Share it with you for your reference. The details are as follows:

The following is a brief introduction:

For example, there is a picture:

A-> B
A-> C
B-> C
B-> D
C-> D
D-> C
E-> F
F-> C

It can be built using a dictionary and a list.

graph = {'A': ['B', 'C'],       'B': ['C', 'D'],       'C': ['D'],       'D': ['C'],       'E': ['F'],       'F': ['C']}

Find a path:

def find_path(graph, start, end, path=[]):    path = path + [start]    if start == end:      return path    if not graph.has_key(start):      return None    for node in graph[start]:      if node not in path:        newpath = find_path(graph, node, end, path)        if newpath: return newpath    return None

Find all paths:

def find_all_paths(graph, start, end, path=[]):    path = path + [start]    if start == end:      return [path]    if not graph.has_key(start):      return []    paths = []    for node in graph[start]:      if node not in path:        newpaths = find_all_paths(graph, node, end, path)        for newpath in newpaths:          paths.append(newpath)    return paths

Find the Shortest Path:

def find_shortest_path(graph, start, end, path=[]):    path = path + [start]    if start == end:      return path    if not graph.has_key(start):      return None    shortest = None    for node in graph[start]:      if node not in path:        newpath = find_shortest_path(graph, node, end, path)        if newpath:          if not shortest or len(newpath) < len(shortest):            shortest = newpath    return shortest

I hope this article will help you with Python programming.