@abstractmethod
    def _initialize(self, X, resp):
        pass
If `sparse` is `True` the transform/fit_transform methods generate a
dataset/ETHPy150Open scikit-learn/scikit-learn/sklearn/mixture/base.py/BaseMixture._initialize--crossover with--dataset/ETHPy150Open machinalis/featureforge/featureforge/flattener.py/FeatureMappingFlattener.__init__