def add_feature(list_1, list_2):
    """
    Adds second input data as features of the first. currently only works with two one-dimensional vectors

    :param list_1: first input of data as list
    :param list_2: second input of data as list
    :return: input data with corresponding feature in second list
    """
    if type(list_1) or type(list_2) is not list:
        list_1 = list(list_1)
        list_2 = list(list_2)
    if type(list_1) and type(list_2) is list:
        assert len(list_1) == len(list_2)
        concatenated_list = []
        i = 0
        while i < len(list_1):
            concatenated_list.append([list_1[i], list_2[i]])
            i += 1
        return concatenated_list
