如何在python中保存和恢复多个变量？

Question

我需要将大约十二个对象保存到文件中,然后再恢复它们.我试图使用带有泡菜和搁置的for循环,但它无法正常工作.

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

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'

Answer 1

如果需要保存多个对象,可以简单地将它们放在单个列表或元组中,例如:

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)

如果您有大量数据,可以通过传递protocol=-1来减小文件大小dump(); pickle然后将使用最佳可用协议而不是默认历史(和更向后兼容)协议.在这种情况下,必须以二进制模式(wb和rb分别)打开文件.

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').

Answer 2

有一个名为的内置库pickle.使用pickle您可以将对象转储到文件并在以后加载它们.

import pickle

f = open('store.pckl', 'wb')
pickle.dump(obj, f)
f.close()

f = open('store.pckl', 'rb')
obj = pickle.load(f)
f.close()

Answer 3

你应该看看搁架和泡菜模块.如果您需要存储大量数据,最好使用数据库

Answer 4

另一种将多个变量保存到 pickle 文件的方法是：

import pickle

a = 3; b = [11,223,435];
pickle.dump([a,b], open("trial.p", "wb"))

c,d = pickle.load(open("trial.p","rb"))

print(c,d) ## To verify

Answer 5

以下方法看起来很简单，可以用于不同大小的变量：

import hickle as hkl
# write variables to filename [a,b,c can be of any size]
hkl.dump([a,b,c], filename)

# load variables from filename
a,b,c = hkl.load(filename)

Answer 6

您可以使用klepto，它为内存、磁盘或数据库提供持久缓存。

dude@hilbert>$ python
Python 2.7.6 (default, Nov 12 2013, 13:26:39) 
[GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from klepto.archives import file_archive
>>> db = file_archive('foo.txt')
>>> db['1'] = 1
>>> db['max'] = max
>>> squared = lambda x: x**2
>>> db['squared'] = squared
>>> def add(x,y):
...   return x+y
... 
>>> db['add'] = add
>>> class Foo(object):
...   y = 1
...   def bar(self, x):
...     return self.y + x
... 
>>> db['Foo'] = Foo
>>> f = Foo()
>>> db['f'] = f  
>>> db.dump()
>>> 

然后，解释器重新启动后...

dude@hilbert>$ python
Python 2.7.6 (default, Nov 12 2013, 13:26:39) 
[GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from klepto.archives import file_archive
>>> db = file_archive('foo.txt')
>>> db
file_archive('foo.txt', {}, cached=True)
>>> db.load()
>>> db
file_archive('foo.txt', {'1': 1, 'add': <function add at 0x10610a0c8>, 'f': <__main__.Foo object at 0x10510ced0>, 'max': <built-in function max>, 'Foo': <class '__main__.Foo'>, 'squared': <function <lambda> at 0x10610a1b8>}, cached=True)
>>> db['add'](2,3)
5
>>> db['squared'](3)
9
>>> db['f'].bar(4)
5
>>> 

在这里获取代码： https: //github.com/uqfoundation