Class _DistanceQuery

mne/surface.py:657–691

Wrapper for fast distance queries.

class _DistanceQuery:
    """Wrapper for fast distance queries."""

    def __init__(self, xhs, method="BallTree"):
        assert method in ("BallTree", "KDTree", "cdist")

        # Fastest for our problems: balltree
        if method == "BallTree":
            try:
                from sklearn.neighbors import BallTree
            except ImportError:
                logger.info(
                    "Nearest-neighbor searches will be significantly "
                    "faster if scikit-learn is installed."
                )
                method = "KDTree"
            else:
                self.query = partial(
                    _safe_query,
                    func=BallTree(xhs).query,
                    reduce=True,
                    return_distance=True,
                )

        # Then KDTree
        if method == "KDTree":
            from scipy.spatial import KDTree

            self.query = KDTree(xhs).query

        # Then the worst: cdist
        if method == "cdist":
            self.query = _CDist(xhs).query

        self.data = xhs


@verbose