如何在python中使用pickle附加？
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How to use append with pickle in python?
提问by Jannat Arora
i need to append to a pickle file (as i don't have the entire dictionary with me at one go). So for doing the same I have written the following code:
我需要附加到一个泡菜文件（因为我没有一次随身携带整个字典）。因此，为了做同样的事情，我编写了以下代码：
import pickle
p={}
p[1]=2
q={}
q['a']=p
p={}
p[2]=0
pickle.dump(q, open("save12.p","ab"))
f={}
f['b']=p
pickle.dump(f,open("save12.p","ab"))
However, when I am loading the pickle file I don't find the value of dictionary f there?????
但是，当我加载泡菜文件时，我在那里找不到字典 f 的值？？？？
Can someone please suggest as to how should I go about appending in a pickle file???
有人可以建议我应该如何添加泡菜文件吗？？？
Also databases like 'dbm' are not working for my need as i am working on windows
像“dbm”这样的数据库也不能满足我的需要，因为我在 Windows 上工作
采纳答案by nneonneo
Pickle streams are entirely self-contained, and so unpickling will unpickle one object at a time.
Pickle 流是完全独立的，因此 unpickling 将一次 unpickle 一个对象。
Therefore, to unpickle multiple streams, you should repeatedly unpickle the file until you get an EOFError:
因此，要解压多个流，您应该反复解压文件，直到出现 EOFError：
>>> f=open('a.p', 'wb')
>>> pickle.dump({1:2}, f)
>>> pickle.dump({3:4}, f)
>>> f.close()
>>>
>>> f=open('a.p', 'rb')
>>> pickle.load(f)
{1: 2}
>>> pickle.load(f)
{3: 4}
>>> pickle.load(f)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
EOFError
so your unpickle code might look like
所以你的 unpickle 代码可能看起来像
import pickle
objs = []
while 1:
try:
objs.append(pickle.load(f))
except EOFError:
break
回答by Rangoli Thakur
#To append to a pickle file
import pickle
p={1:2}
q={3:4}
filename="picklefile"
with open(filename, 'a+') as fp:
pickle.dump(p,fp)
pickle.dump(q,fp)
#To load from pickle file
data = []
with open(filename, 'rb') as fr:
try:
while True:
data.append(pickle.load(fr))
except EOFError:
pass
