Explain prediction of a linear regressor.

    See :func:`eli5.explain_prediction` for description of
    ``top``, ``top_targets``, ``target_names``, ``targets``,
    ``feature_names``, ``feature_re`` and ``feature_filter`` parameters.

    ``vec`` is a vectorizer instance used to transform
    raw features to the input of the classifier ``clf``;
    you can pass it instead of ``feature_names``.

    ``vectorized`` is a flag which tells eli5 if ``doc`` should be
    passed through ``vec`` or not. By default it is False, meaning that
    if ``vec`` is not None, ``vec.transform([doc])`` is passed to the
    regressor ``reg``. Set it to True if you're passing ``vec``,
    but ``doc`` is already vectorized.

def explain_prediction_linear_regressor(reg, doc,
                                        vec=None,
                                        top=None,
                                        top_targets=None,
                                        target_names=None,
                                        targets=None,
                                        feature_names=None,
                                        feature_re=None,
                                        feature_filter=None,
                                        vectorized=False):
    """
    Explain prediction of a linear regressor.

    See :func:`eli5.explain_prediction` for description of
    ``top``, ``top_targets``, ``target_names``, ``targets``,
    ``feature_names``, ``feature_re`` and ``feature_filter`` parameters.

    ``vec`` is a vectorizer instance used to transform
    raw features to the input of the classifier ``clf``;
    you can pass it instead of ``feature_names``.

    ``vectorized`` is a flag which tells eli5 if ``doc`` should be
    passed through ``vec`` or not. By default it is False, meaning that
    if ``vec`` is not None, ``vec.transform([doc])`` is passed to the
    regressor ``reg``. Set it to True if you're passing ``vec``,
    but ``doc`` is already vectorized.
    """
    if isinstance(reg, (SVR, NuSVR)) and reg.kernel != 'linear':
        return explain_prediction_sklearn_not_supported(reg, doc)

    vec, feature_names = handle_vec(reg, doc, vec, vectorized, feature_names)
    X = get_X(doc, vec=vec, vectorized=vectorized, to_dense=True)

    score, = reg.predict(X)

    if has_intercept(reg):
        X = add_intercept(X)
    x = get_X0(X)

    feature_names, flt_indices = feature_names.handle_filter(
        feature_filter, feature_re, x)

    res = Explanation(
        estimator=repr(reg),
        method='linear model',
        targets=[],
        is_regression=True,
    )
    assert res.targets is not None

    _weights = _linear_weights(reg, x, top, feature_names, flt_indices)
    names = get_default_target_names(reg)
    display_names = get_target_display_names(names, target_names, targets,
                                             top_targets, score)

    if is_multitarget_regressor(reg):
        for label_id, label in display_names:
            target_expl = TargetExplanation(
                target=label,
                feature_weights=_weights(label_id),
                score=score[label_id],
            )
            add_weighted_spans(doc, vec, vectorized, target_expl)
            res.targets.append(target_expl)
    else:
        target_expl = TargetExplanation(
            target=display_names[0][1],
            feature_weights=_weights(0),
            score=score,
        )
        add_weighted_spans(doc, vec, vectorized, target_expl)
        res.targets.append(target_expl)

    return res