Function _scale_params

mne/coreg.py:856–890

Assemble parameters for scaling. Returns ------- subjects_dir : path-like Subjects directory. subject_from : str Name of the source subject. scale : array Scaling factor, either shape=() for uniform scaling or shape=(3,) for non-uniform scaling.

(subject_to, subject_from, scale, subjects_dir)

def _scale_params(subject_to, subject_from, scale, subjects_dir):
    """Assemble parameters for scaling.

    Returns
    -------
    subjects_dir : path-like
        Subjects directory.
    subject_from : str
        Name of the source subject.
    scale : array
        Scaling factor, either shape=() for uniform scaling or shape=(3,) for
        non-uniform scaling.
    uniform : bool
        Whether scaling is uniform.
    """
    subjects_dir = get_subjects_dir(subjects_dir, raise_error=True)
    if (subject_from is None) != (scale is None):
        raise TypeError(
            "Need to provide either both subject_from and scale parameters, or neither."
        )

    if subject_from is None:
        cfg = read_mri_cfg(subject_to, subjects_dir)
        subject_from = cfg["subject_from"]
        n_params = cfg["n_params"]
        assert n_params in (1, 3)
        scale = cfg["scale"]
    scale = np.atleast_1d(scale)
    if scale.ndim != 1 or scale.shape[0] not in (1, 3):
        raise ValueError(
            "Invalid shape for scale parameter. Need scalar or array of length 3. Got "
            f"shape {scale.shape}."
        )
    n_params = len(scale)
    return str(subjects_dir), subject_from, scale, n_params == 1


@verbose