如何在python中保存和恢复多个变量? [英] How do I save and restore multiple variables in python?

问题描述

我需要将大约十几个对象保存到一个文件中，然后再恢复它们.我尝试将 for 循环与 pickle 和 shelve 一起使用，但效果不佳.

I need to save about a dozen objects to a file and then restore them later. I've tried to use a for loop with pickle and shelve but it didn't work right.

编辑.
我试图保存的所有对象都在同一个类中(我之前应该提到过这一点)，我没有意识到我可以像这样保存整个类:

Edit.
All of the objects that I was trying to save were in the same class (I should have mentioned this before), and I didn't realize that I could just save the whole class like this:

import pickle
def saveLoad(opt):
    global calc
    if opt == "save":
        f = file(filename, 'wb')
        pickle.dump(calc, f, 2)
        f.close
        print 'data saved'
    elif opt == "load":
        f = file(filename, 'rb')
        calc = pickle.load(f)
    else:
        print 'Invalid saveLoad option'

推荐答案

如果您需要保存多个对象，您可以简单地将它们放在一个列表或元组中，例如:

If you need to save multiple objects, you can simply put them in a single list, or tuple, for instance:

import pickle

# obj0, obj1, obj2 are created here...

# Saving the objects:
with open('objs.pkl', 'w') as f:  # Python 3: open(..., 'wb')
    pickle.dump([obj0, obj1, obj2], f)

# Getting back the objects:
with open('objs.pkl') as f:  # Python 3: open(..., 'rb')
    obj0, obj1, obj2 = pickle.load(f)

如果你有很多数据，你可以通过将protocol=-1传递给dump()来减小文件大小；pickle 然后将使用最好的可用协议而不是默认的历史(和向后兼容)协议.在这种情况下，文件必须以二进制模式打开(分别为 wb 和 rb).

If you have a lot of data, you can reduce the file size by passing protocol=-1 to dump(); pickle will then use the best available protocol instead of the default historical (and more backward-compatible) protocol. In this case, the file must be opened in binary mode (wb and rb, respectively).

二进制模式也应该与 Python 3 一起使用，因为它的默认协议产生二进制(即非文本)数据(写入模式 'wb' 和读取模式 'rb').

The binary mode should also be used with Python 3, as its default protocol produces binary (i.e. non-text) data (writing mode 'wb' and reading mode 'rb').

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