Function combine_transforms

mne/transforms.py:519–568

Combine two transforms. Parameters ---------- t_first : dict First transform. t_second : dict Second transform. fro : int From coordinate frame. to : int To coordinate frame. Returns ------- trans : dict Combined transform

(t_first, t_second, fro, to)

def combine_transforms(t_first, t_second, fro, to):
    """Combine two transforms.

    Parameters
    ----------
    t_first : dict
        First transform.
    t_second : dict
        Second transform.
    fro : int
        From coordinate frame.
    to : int
        To coordinate frame.

    Returns
    -------
    trans : dict
        Combined transformation.
    """
    fro = _to_const(fro)
    to = _to_const(to)
    if t_first["from"] != fro:
        raise RuntimeError(
            'From mismatch: {fro1} ("{cf1}") != {fro2} ("{cf2}")'.format(
                fro1=t_first["from"],
                cf1=_coord_frame_name(t_first["from"]),
                fro2=fro,
                cf2=_coord_frame_name(fro),
            )
        )
    if t_first["to"] != t_second["from"]:
        raise RuntimeError(
            'Transform mismatch: t1["to"] = {to1} ("{cf1}"), '
            't2["from"] = {fro2} ("{cf2}")'.format(
                to1=t_first["to"],
                cf1=_coord_frame_name(t_first["to"]),
                fro2=t_second["from"],
                cf2=_coord_frame_name(t_second["from"]),
            )
        )
    if t_second["to"] != to:
        raise RuntimeError(
            'To mismatch: {to1} ("{cf1}") != {to2} ("{cf2}")'.format(
                to1=t_second["to"],
                cf1=_coord_frame_name(t_second["to"]),
                to2=to,
                cf2=_coord_frame_name(to),
            )
        )
    return Transform(fro, to, np.dot(t_second["trans"], t_first["trans"]))


@verbose