gistfile1.txt

import random

import networkx as nx
from networkx.exception import NetworkXNoCycle


class Node(object):

    def __init__(self, name, dependencies):
        self.name = name
        self.dependencies = dependencies

    def __str__(self):
        return "Name: %s - Depencencies: %s" % (self.name, [x.name for x  in self.dependencies])

def cycle_detector(node):
    visiting = {}

    def _cycle_detector(node):
        if node in visiting:
            raise ImportError("Depedency Cycle")

        visiting[node] = True
        [_cycle_detector(n) for n in node.dependencies]

    _cycle_detector(node)


def generate_graph(size):
    nodes = [Node(i, None) for i in range(size)]

    for i in range(size):
        nodes[i].dependencies = [x for x in nodes if random.random() > 0.99 and nodes[i] != x]

    print "\n".join([str(x) for x in nodes])
    return nodes
SIZE = 60

nodes = generate_graph(SIZE)

found_cycle = False

for i in range(SIZE):
    try:
        cycle_detector(nodes[i])
    except ImportError:
        print "Dependency Cycle for %s" % i

        found_cycle = True


g = nx.DiGraph()

[g.add_node(x.name) for x in nodes]

for x in nodes:
    [g.add_edge(x.name, y.name) for y in x.dependencies]

try:
    print nx.find_cycle(g, orientation='original')
except Exception as ex:
    if found_cycle:
        print "Errore!!"