For multi-class classification in SGDClassifier how do I tell if it is using one-vs-rest or one-vs-one by default?
It's there in the User guide [Link]

&quot;....SGDClassifier supports multi-class classification by combining multiple binary classifiers in a “one versus all” (OVA) scheme. For each of the  classes, a binary classifier is learned that discriminates between that and all other  classes. At testing time, we compute the confidence score (i.e. the signed distances to the hyperplane) for each classifier and choose the class with the highest confidence....&quot;