def read_pos_data(filename):
    """
    Read data from file which looks like (sec, nsec, x, y, z)
        0 8000000 -14 0 0.149843
        1 12000000 -13.9997 -1.6e-05 0.117777
        2 16000000 -13.9997 -1.9e-05 0.117841
    """
    arr = []
    for line in open(filename):
        sec, nsec, x, y, z = [float(a) for a in line.split()]
        arr.append((sec + nsec/1_000_000_000, (x, y, z)))
    return arr