we should probably improve the docs on the ovr. iirc the user guide was already
very explicit, maybe add something to the docstring?
abhi: did you read the user guide on the one vs rest classifier? how could we
improve it to make things more clear?
Mathieu Blondel <[email protected]> schrieb:
>On Tue, Nov 6, 2012 at 9:33 AM, Abhi <[email protected]> wrote:
>
>> Hello,
>> I have been reading and testing examples around the sklearn
>> documentation and
>> am not too clear on few things and would appreciate any help
>regarding the
>> following questions:
>> 1) What would be the advantage of training LogisticRegression vs
>> OneVsRestClassifier(LogisticRegression()) for multiclass. (I
>understand
>> the latter would basically train n_classes classifiers).
>>
>
>They actually do the same. liblinear uses one-vs-rest everywhere except
>for
>the crammer-singer SVM formulation.
>I wonder why we keep getting this question.
>
>
>> 2) Isnt SGDClassifier(loss='log') better than LogisticRegression for
>large
>> sparse datasets? If so, why?
>>
>
>It's faster to train *once* you chose the learning rate, which is
>usually a
>pain. You can also try LogisticRegression(tol=1e-2) or
>LogisticRegression(tol=1e-1).
>
>
>> 3) If I need predict_proba for just the best class match from the
>> multiclass
>> classifier, can I use OneVsRestClassifier(SGDClassifier())
>>
>
>In that case you can just use predict().
>
>Mathieu
>
>
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