Compute the micro average scores for the ROCAUC curves.

def _score_micro_average(self, y, y_pred, classes, n_classes):
        """
        Compute the micro average scores for the ROCAUC curves.
        """
        # Convert y to binarized array for micro and macro scores
        y = label_binarize(y, classes=classes)
        if n_classes == 2:
            y = np.hstack((1-y, y))

        # Compute micro-average
        self.fpr[MICRO], self.tpr[MICRO], _ = roc_curve(y.ravel(), y_pred.ravel())
        self.roc_auc[MICRO] = auc(self.fpr[MICRO], self.tpr[MICRO])