def explain_rf_feature_importance(estimator,
                                  vec=None,
                                  top=_TOP,
                                  target_names=None,  # ignored
                                  targets=None,  # ignored
                                  feature_names=None,
                                  feature_re=None,
                                  feature_filter=None,
                                  ):
    """
    Return an explanation of a tree-based ensemble estimator.

    See :func:`eli5.explain_weights` for description of
    ``top``, ``feature_names``, ``feature_re`` and ``feature_filter``
    parameters.

    ``target_names`` and ``targets`` parameters are ignored.

    ``vec`` is a vectorizer instance used to transform
    raw features to the input of the estimator (e.g. a fitted
    CountVectorizer instance); you can pass it instead of ``feature_names``.
    """
    coef = estimator.feature_importances_
    trees = np.array(estimator.estimators_).ravel()
    coef_std = np.std([tree.feature_importances_ for tree in trees], axis=0)
    return get_feature_importance_explanation(estimator, vec, coef,
        coef_std=coef_std,
        feature_names=feature_names,
        feature_filter=feature_filter,
        feature_re=feature_re,
        top=top,
        description=DESCRIPTION_RANDOM_FOREST,
        is_regression=isinstance(estimator, RegressorMixin),
    )