python pickle.dumps AssertionError

Question

我想醃一個包含兩個其他實例列表的類實例。兩個列表中的實例具有相互引用實例的屬性。這裏是類。

import pickle 
from copy import copy 

class Graph: 
    def __init__(self): 
     self.vertices = {} 
     self.edges = set() 
    def __repr__(self): 
     return "\n".join(map(str, sorted(self.vertices, key=lambda v:v.id))) 

class Edge: 
    def __init__(self, vfrom, vto): 
     self.vfrom = vfrom 
     self.vto = vto 
    def __hash__(self): 
     return hash((self.vto, self.vfrom)) 
    def __repr__(self): 
     return str(self.vto.id) 
    def __getstate__(self): 
     vfrom = copy(self.vfrom) 
     vfrom.del_outgoing(self) 
     vto = copy(self.vto) 
     vto.del_incoming(self) 
     self.__dict__.update({"vfrom":vfrom, "vto":vto, }) 
     return self.__dict__ 
    def __setstate__(self, state): 
     self.__dict__.update(state) 
     self.__dict__["vfrom"].add_outgoing(self) 
     self.__dict__["vto"].add_incoming(self) 

class Vertex: 
    def __init__(self, id): 
     self.id = id 
     self.incoming = set() 
     self.outgoing = set() 
    def __repr__(self): 
     return "Vertex %d -> %s"%(self.id, ", ".join(map(str, self.outgoing))) 
    def __hash__(self): 
     return hash(self.id) 
    def add_incoming(self, edge): 
     if not edge in self.incoming: 
      self.incoming.add(edge) 
    def add_outgoing(self, edge): 
     if not edge in self.outgoing: 
      self.outgoing.add(edge) 
    def del_incoming(self, edge): 
     self.incoming.discard(edge) 
    def del_outgoing(self, edge): 
     self.outgoing.discard(edge) 

當我按照如下方式對一個簡單的圖進行醃製時，我得到了一個AssertionError。

>>> v0 = Vertex(0) 
>>> v1 = Vertex(1) 
>>> e0to1 = Edge(v0, v1) 
>>> v0.add_outgoing(e0to1) 
>>> v1.add_incoming(e0to1) 
>>> g = Graph() 
>>> g.vertices[v0] = v0 
>>> g.vertices[v1] = v1 
>>> g.edges.add(e0to1) 
>>> g.edges.add(e0to1) 
>>> v2 = Vertex(2) 
>>> e0to2 = Edge(v0, v2) 
>>> v0.add_outgoing(e0to2) 
>>> v2.add_incoming(e0to2) 
>>> g.vertices[v2] = v2 
>>> g.edges.add(e0to2) 
>>> 
>>> print g 
Vertex 0 -> 2, 1 
Vertex 1 -> 
Vertex 2 -> 
>>> p = pickle.dumps(g) 
Traceback (most recent call last): 
    File "<stdin>", line 1, in <module> 
    File "/usr/lib/python2.6/pickle.py", line 1366, in dumps 
    Pickler(file, protocol).dump(obj) 
    File "/usr/lib/python2.6/pickle.py", line 224, in dump 
    self.save(obj) 
    File "/usr/lib/python2.6/pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "/usr/lib/python2.6/pickle.py", line 725, in save_inst 
    save(stuff) 
    File "/usr/lib/python2.6/pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "/usr/lib/python2.6/pickle.py", line 649, in save_dict 
    self._batch_setitems(obj.iteritems()) 
    File "/usr/lib/python2.6/pickle.py", line 663, in _batch_setitems 
    save(v) 
    File "/usr/lib/python2.6/pickle.py", line 331, in save 
    self.save_reduce(obj=obj, *rv) 
    File "/usr/lib/python2.6/pickle.py", line 401, in save_reduce 
    save(args) 
    File "/usr/lib/python2.6/pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "/usr/lib/python2.6/pickle.py", line 562, in save_tuple 
    save(element) 
    File "/usr/lib/python2.6/pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "/usr/lib/python2.6/pickle.py", line 600, in save_list 
    self._batch_appends(iter(obj)) 
    File "/usr/lib/python2.6/pickle.py", line 615, in _batch_appends 
    save(x) 
    File "/usr/lib/python2.6/pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "/usr/lib/python2.6/pickle.py", line 725, in save_inst 
    save(stuff) 
    File "/usr/lib/python2.6/pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "/usr/lib/python2.6/pickle.py", line 649, in save_dict 
    self._batch_setitems(obj.iteritems()) 
    File "/usr/lib/python2.6/pickle.py", line 663, in _batch_setitems 
    save(v) 
    File "/usr/lib/python2.6/pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "/usr/lib/python2.6/pickle.py", line 725, in save_inst 
    save(stuff) 
    File "/usr/lib/python2.6/pickle.py", line 286, in save 
    f(self, obj) # Call unbound method with explicit self 
    File "/usr/lib/python2.6/pickle.py", line 649, in save_dict 
    self._batch_setitems(obj.iteritems()) 
    File "/usr/lib/python2.6/pickle.py", line 663, in _batch_setitems 
    save(v) 
    File "/usr/lib/python2.6/pickle.py", line 331, in save 
    self.save_reduce(obj=obj, *rv) 
    File "/usr/lib/python2.6/pickle.py", line 405, in save_reduce 
    self.memoize(obj) 
    File "/usr/lib/python2.6/pickle.py", line 244, in memoize 
    assert id(obj) not in self.memo 
AssertionError 

我在v2被移除時工作。

>>> v0 = Vertex(0) 
>>> v1 = Vertex(1) 
>>> e0to1 = Edge(v0, v1) 
>>> v0.outgoing.add(e0to1) 
>>> v1.incoming.add(e0to1) 
>>> g = Graph() 
>>> g.vertices[v0] = v0 
>>> g.vertices[v1] = v1 
>>> g.edges.add(e0to1) 
>>> g.edges.add(e0to1) 
>>> import cPickle as pickle 
>>> p = pickle.dumps(g) 
>>> print pickle.loads(p) 
Vertex 0 -> 1 
Vertex 1 -> 

你有什麼想法嗎？

Answer 1

舊的pickle協議無法處理某些類型的數據。要解決您的問題，請使用pickle.HIGHEST_PROTOCOL

>>> p = pickle.dumps(g) 
    File "/usr/lib/python2.6/pickle.py", line 244, in memoize 
    assert id(obj) not in self.memo 
AssertionError: 
>>> p = pickle.dumps(g, pickle.HIGHEST_PROTOCOL) 
>>> # No problem!