def get_notable_indices(matrix, top_k=5):
    """
    Return dict of top k and bottom k features useful from matrix.

    Args:
        matrix: 1d numpy array
        top_k: defaults to top and bottom 5 indices
    """
    important_features = matrix.argsort()[-top_k:][::-1]
    unimportant_features = matrix.argsort()[:-1][:top_k]
    return {'important_indices': important_features,
            'unimportant_indices': unimportant_features}