Computes regression score of tdfidf transformed features
        Parameters
        ----------
        category : str
            category name to score
        clf : sklearn regressor

        Returns
        -------
        coefficient array

def get_logreg_coefs(self, category, clf=LogisticRegression()):
        ''' Computes regression score of tdfidf transformed features
        Parameters
        ----------
        category : str
            category name to score
        clf : sklearn regressor

        Returns
        -------
        coefficient array
        '''
        self._fit_tfidf_model(category, clf)
        return clf.coef_[0]