An option to indicate if a “negative” class should be created
in the case of multinomial classification. For the “negative”
class the model will train on all the negatives, and if
a new label is encountered in the target column, its
coefficients are initialized to the current “negative” class coefficients.
negative_class is set to
False, the initial coefficients
This option is read-only for a trained model.
The exception is raised when trying to change this option for a model that has already been trained.