python 做推荐算法，遇到MemoryError错误，求破

[pcat2015]

[code=python]
def ItemSim(self,train = None):
train = train or self.traindata()
Item_count = dict() #浏览过每种物品的人数#
ItemSimcount = dict() #既浏览过i，又浏览过j的某人的时间加权#
for users,items in train.items():
for i,tui in items.items():
Item_count.setdefault(i,0)
Item_count[i] += 1
for j,tuj in items.items():
if i == j:
continue
ItemSimcount.setdefault(users,{})
ItemSimcount[users].setdefault(i,{})
ItemSimcount[users][i].setdefault(j,0)
ItemSimcount[users][i][j] += 1
self.ItemSimlist = dict()
for user,rec in ItemSimcount.items():
self.ItemSimlist.setdefault(user,{})
for i ,related_items in rec.items():
self.ItemSimlist[user].setdefault(i,{})
for j, cij in related_items.items(): #cij：计算出的分子，存放喜欢i和j的某用户的时间加权#
self.ItemSimlist[user][i].setdefault(j,0)
self.ItemSimlist[user][i][j] = cij / math.sqrt(Item_count[i] * Item_count[j] * 1.0)
[code]
报错：
cf.ItemSim()
File "F:\PPractice\ml-100k\log.py", line 97, in ItemSim
self.ItemSimlist[user][i].setdefault(j,0)
MemoryError

怎么破，求助

[thomashtq]

加载到内存的数据量太大导致的。