def keepsaccade(i,
                j,
                sim,
                data
                ):
    """
    Helper function for scanpath simplification. If no simplification can be
    performed on a particular saccade, this functions stores the original data.
    :param i: current index
    :param j: current index
    :param sim: dict with current similarities
    :param data: original dict with vector based scanpath representation
    """
    for t, k in (('sac', 'lenx'),
                 ('sac', 'leny'),
                 ('sac', 'x'),
                 ('sac', 'y'),
                 ('sac', 'theta'),
                 ('sac', 'rho'),
                 ('fix', 'dur')):
        sim[t][k].insert(j, data[t][k][i])

    return i + 1, j + 1