Class Transform

mne/transforms.py:95–204

A transform. Parameters ---------- fro : str | int The starting coordinate frame. See notes for valid coordinate frames. to : str | int The ending coordinate frame. See notes for valid coordinate frames. trans : array of shape (4, 4) | None The transforma

class Transform(dict):
    """A transform.

    Parameters
    ----------
    fro : str | int
        The starting coordinate frame. See notes for valid coordinate frames.
    to : str | int
        The ending coordinate frame. See notes for valid coordinate frames.
    trans : array of shape (4, 4) | None
        The transformation matrix. If None, an identity matrix will be
        used.

    Notes
    -----
    Valid coordinate frames are ``'meg'``, ``'mri'``, ``'mri_voxel'``,
    ``'head'``, ``'mri_tal'``, ``'ras'``, ``'fs_tal'``, ``'ctf_head'``,
    ``'ctf_meg'``, ``'unknown'``.
    """

    def __init__(self, fro, to, trans=None):
        super().__init__()
        # we could add some better sanity checks here
        fro = _to_const(fro)
        to = _to_const(to)
        trans = np.eye(4) if trans is None else np.asarray(trans, np.float64)
        if trans.shape != (4, 4):
            raise ValueError(f"Transformation must be shape (4, 4) not {trans.shape}")
        self["from"] = fro
        self["to"] = to
        self["trans"] = trans

    def __repr__(self):  # noqa: D105
        with np.printoptions(suppress=True):  # suppress scientific notation
            return "<Transform | {fro}->{to}>\n{trans}".format(
                fro=_coord_frame_name(self["from"]),
                to=_coord_frame_name(self["to"]),
                trans=self["trans"],
            )

    def __eq__(self, other, rtol=0.0, atol=0.0):
        """Check for equality.

        Parameter
        ---------
        other : instance of Transform
            The other transform.
        rtol : float
            Relative tolerance.
        atol : float
            Absolute tolerance.

        Returns
        -------
        eq : bool
            True if the transforms are equal.
        """
        return (