def _map_groups_to_params(params):
    """Map the group name to the ColumnDataSource friendly parameter names.

    Args:
        params (pd.DataFrame):
            DataFrame with the parameter values and additional information such as the
            "group" column and Index.

    Returns:
        group_to_params (dict):
            Keys are the values of the "group" column. The values are lists with
            bokeh friendly strings of the index tuples identifying the parameters
            that belong to this group. Parameters where group is None are ignored.

    """
    group_to_params = {}
    actual_groups = [group for group in params["group"].unique() if group is not None]
    for group in actual_groups:
        group_to_params[group] = list(params[params["group"] == group]["name"])
    return group_to_params