def _get_xlabel(self):
        """
        Determines the xlabel based on the underlying data structure
        """
        # Return user-specified label
        if self.xlabel:
            return self.xlabel

        # Label for coefficients
        if hasattr(self.estimator, "coef_"):
            if self.relative:
                return "relative coefficient magnitude"
            return "coefficient value"

        # Default label for feature_importances_
        if self.relative:
            return "relative importance"
        return "feature importance"
Determines the xlabel based on the underlying data structure