Unable to pickle the estimator VW_Classifier

[viveksck]

Steps to reproduce: Use example_sklearn.py.

Try to pickle the best_estimator returned after the GridSearchCV: (pickle gs.bestestimator)

You will get the error: Traceback (most recent call last): File "example_sklearn1.py", line 66, in main() File "example_sklearn1.py", line 63, in main joblib.dump(estimator, "m.pkl") File "/usr/local/lib/python2.7/dist-packages/sklearn/externals/joblib/numpy_pickle.py", line 367, in dump pickler.dump(value) File "/usr/lib/python2.7/pickle.py", line 224, in dump self.save(obj) File "/usr/local/lib/python2.7/dist-packages/sklearn/externals/joblib/numpy_pickle.py", line 249, in save return Pickler.save(self, obj) File "/usr/lib/python2.7/pickle.py", line 331, in save self.save_reduce(obj=obj, _rv) File "/usr/lib/python2.7/pickle.py", line 419, in save_reduce save(state) File "/usr/local/lib/python2.7/dist-packages/sklearn/externals/joblib/numpy_pickle.py", line 249, in save return Pickler.save(self, obj) File "/usr/lib/python2.7/pickle.py", line 286, in save f(self, obj) # Call unbound method with explicit self File "/usr/lib/python2.7/pickle.py", line 649, in save_dict self._batch_setitems(obj.iteritems()) File "/usr/lib/python2.7/pickle.py", line 681, in _batch_setitems save(v) File "/usr/local/lib/python2.7/dist-packages/sklearn/externals/joblib/numpy_pickle.py", line 249, in save return Pickler.save(self, obj) File "/usr/lib/python2.7/pickle.py", line 286, in save f(self, obj) # Call unbound method with explicit self File "/usr/lib/python2.7/pickle.py", line 725, in save_inst save(stuff) File "/usr/local/lib/python2.7/dist-packages/sklearn/externals/joblib/numpy_pickle.py", line 249, in save return Pickler.save(self, obj) File "/usr/lib/python2.7/pickle.py", line 286, in save f(self, obj) # Call unbound method with explicit self File "/usr/lib/python2.7/pickle.py", line 649, in save_dict self._batch_setitems(obj.iteritems()) File "/usr/lib/python2.7/pickle.py", line 681, in _batch_setitems save(v) File "/usr/local/lib/python2.7/dist-packages/sklearn/externals/joblib/numpy_pickle.py", line 249, in save return Pickler.save(self, obj) File "/usr/lib/python2.7/pickle.py", line 331, in save self.save_reduce(obj=obj, rv) File "/usr/lib/python2.7/pickle.py", line 396, in save_reduce save(cls) File "/usr/local/lib/python2.7/dist-packages/sklearn/externals/joblib/numpy_pickle.py", line 249, in save return Pickler.save(self, obj) File "/usr/lib/python2.7/pickle.py", line 286, in save f(self, obj) # Call unbound method with explicit self File "/usr/lib/python2.7/pickle.py", line 748, in save_global (obj, module, name)) _pickle.PicklingError: Can't pickle <type 'instancemethod'>: it's not found as builtin.instancemethod Exception raised <bound method VW.push_instance_stdin of <vowpal_porpoise.vw.VW instance at 0x9dc714c>>** My debugging led me to think the following object is not picklable and hence the issue.

[kolesman]

Indeed, Pickle is not able to serialize instance method. There are few non-trivial methods to come over this.

But I would reccomnd you to Pickle whole scikit-learn classifier object. Then you can UnPickle it and call estimator.

[viveksck]

Thanks . I actually used a workaround described here to get the object to pickle": http://stackoverflow.com/questions/14306683/cpickle-ignore-stuff-it-cant-serialize-instead-of-raising-an-exception

[goite]

Hi viveksck. I'm having the same problem. Could you please post the code you created for fixing it? Many thanks!

[viveksck]

Hi, I will give you the diff tonight. I was away for a couple of days. Sorry about that.

Thanks. Vivek.

On Wed, Mar 5, 2014 at 8:00 AM, goite notifications@github.com wrote:

Hi viveksck. I'm having the same problem. Could you please post the code you created for fixing it? Many thanks!

Reply to this email directly or view it on GitHubhttps://github.com/josephreisinger/vowpal_porpoise/issues/4#issuecomment-36739494 .

[viveksck]

The workaround I used is pasted below. Paste this code in the file where you would like to pickle the model. Hope this helps.

import pickle

# Code to pickle a VW model
import copy_reg
from types import FunctionType, FileType, MethodType
def stub_pickler(obj):
    return stub_unpickler, ()
def stub_unpickler():
    return "STUB"

copy_reg.pickle(MethodType, stub_pickler, stub_unpickler)
copy_reg.pickle(FileType,   stub_pickler, stub_unpickler)
copy_reg.pickle(FunctionType, stub_pickler, stub_unpickler)