unpickling Set as set

[Amir Michail]

Hi,

Is there an easy way to unpickle the older Set as the newer set behind
the scenes when using shelve?

Amir

[Nick Vatamaniuc]

Re: unpickling Set as set


The two are not of the same type:

---------------------------------
In : import sets
In : s1=sets.Set([1,2,3])

In : s2=set([1,2,3])

In: type(s1)
Out: <class 'sets.Set'>

In : type(s2)
Out: <type 'set'>

In : s1==s2
Out: False # oops!

In: s2==set(s1)
Out: True # aha!
----------------------------------

You'll have to just cast:
unpickled_set=s et(unpickled_se t)

-Nick V.


Amir Michail wrote:

Hi,
>
Is there an easy way to unpickle the older Set as the newer set behind
the scenes when using shelve?
>
Amir

[George Sakkis]

Re: unpickling Set as set

Nick Vatamaniuc wrote:

The two are not of the same type:
>
---------------------------------
In : import sets
In : s1=sets.Set([1,2,3])
>
In : s2=set([1,2,3])
>
In: type(s1)
Out: <class 'sets.Set'>
>
In : type(s2)
Out: <type 'set'>
>
In : s1==s2
Out: False # oops!
>
In: s2==set(s1)
Out: True # aha!
----------------------------------
>
You'll have to just cast:
unpickled_set=s et(unpickled_se t)
>
-Nick V.

Or you may have this done automatically by hacking the Set class:

from sets import Set
import cPickle as pickle

Set.__reduce__ = lambda self: (set, (self._data,))

s = Set([1,2,3])
x = pickle.dumps(s)
print pickle.loads(x)


This doesn't work though if you have already pickled the Set before
replacing its __reduce__, so it may not necessarily be what you want.
If there is a way around it, I'd like to know it.

George

[Gabriel G]

Re: unpickling Set as set

At Wednesday 8/11/2006 05:26, George Sakkis wrote:

>Or you may have this done automatically by hacking the Set class:
>
>from sets import Set
>import cPickle as pickle
>
>Set.__reduce __ = lambda self: (set, (self._data,))
>
>s = Set([1,2,3])
>x = pickle.dumps(s)
>print pickle.loads(x)
>
>
>This doesn't work though if you have already pickled the Set before
>replacing its __reduce__, so it may not necessarily be what you want.
>If there is a way around it, I'd like to know it.

Perhaps registering a suitable reduce function in the copy_reg module.
If the sets were pickled alone, and it's not too much trouble, using:
a_set = set(a_set) just after unpickling may be enough.
And if they were instance attributes, __setstate__ on the class can
do the conversion.


--
Gabriel Genellina
Softlab SRL

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