def get_summed_tfidf(idx_list, len_output):
    if len(idx_list) == 0:
        return np.zeros(len_output)
    elif idx_list[0] == -1:
        return word_data_all_summed
    else:
        word_data = tfidf_vectors[idx_list, :]
        word_data = word_data.sum(axis=0)
        word_data = np.squeeze(np.asarray(word_data))
        return word_data