Apr 13, 2020 · Apr 10, 2020 · Apr 10, 2020 · Apr 10, 2020 · Apr 10, 2020 · Apr 10, 2020
diff --git a/lib/matplotlib/transforms.py b/lib/matplotlib/transforms.py
 class Bbox(BboxBase):
    """
    A mutable bounding box.

    Examples
    --------
    **Create from known bounds**

    The default constructor takes the boundary "points" ``[[xmin, ymin],
    [xmax, ymax]]``.

        >>> Bbox([[1, 1], [3, 7]])
        Bbox([[1.0, 1.0], [3.0, 7.0]])

    Alternatively, a Bbox can be created from the flattened points array, the
    so-called "extents" ``(xmin, ymin, xmax, ymax)``

        >>> Bbox.from_extents(1, 1, 3, 7)
        Bbox([[1.0, 1.0], [3.0, 7.0]])

    or from the "bounds" ``(xmin, ymin, width, height)``.

        >>> Bbox.from_bounds(1, 1, 2, 6)
        Bbox([[1.0, 1.0], [3.0, 7.0]])

    **Create from collections of points**

    The "empty" object for accumulating Bboxs is the null bbox, which is a
    stand-in for the empty set.

        >>> Bbox.null()
        Bbox([[inf, inf], [-inf, -inf]])

    Adding points to the null bbox will give you the bbox of those points.

        >>> box = Bbox.null()
        >>> box.update_from_data_xy([[1, 1]])
        >>> box
        Bbox([[1.0, 1.0], [1.0, 1.0]])
        >>> box.update_from_data_xy([[2, 3], [3, 2]], ignore=False)
        >>> box
        Bbox([[1.0, 1.0], [3.0, 3.0]])

    Setting ``ignore=True`` is equivalent to starting over from a null bbox.

        >>> box.update_from_data_xy([[1, 1]], ignore=True)
        >>> box
        Bbox([[1.0, 1.0], [1.0, 1.0]])

    .. warning::

        It is recommended to always specify ``ignore`` explicitly.  If not, the
        default value of ``ignore`` can be changed at any time by code with
        access to your Bbox, for example using the method `~.Bbox.ignore`.

    **Properties of the ``null`` bbox**

    .. note::

        The current behavior of `Bbox.null()` may be surprising as it does
        not have all of the properties of the "empty set", and as such does
        not behave like a "zero" object in the mathematical sense. We may
        change that in the future (with a deprecation period).

    The null bbox is the identity for intersections

        >>> Bbox.intersection(Bbox([[1, 1], [3, 7]]), Bbox.null())
        Bbox([[1.0, 1.0], [3.0, 7.0]])

    except with itself, where it returns the full space.

        >>> Bbox.intersection(Bbox.null(), Bbox.null())
        Bbox([[-inf, -inf], [inf, inf]])

    A union containing null will always return the full space (not the other
    set!)

        >>> Bbox.union([Bbox([[0, 0], [0, 0]]), Bbox.null()])
        Bbox([[-inf, -inf], [inf, inf]])
    """

    def __init__(self, points, **kwargs):
        ----------
        points : ndarray
            A 2x2 numpy array of the form ``[[x0, y0], [x1, y1]]``.

        Notes
        -----
        If you need to create a `Bbox` object from another form
        of data, consider the static methods :meth:`unit`,
        :meth:`from_bounds` and :meth:`from_extents`.
        """
        BboxBase.__init__(self, **kwargs)
        points = np.asarray(points, float)
Original file line number	Diff line number	Diff line change
Expand Up		@@ -682,6 +682,82 @@ def intersection(bbox1, bbox2):
		class Bbox(BboxBase):
		"""
		A mutable bounding box.

		Examples
		--------
		Create from known bounds

		The default constructor takes the boundary "points" ``[[xmin, ymin],
		[xmax, ymax]]``.

		>>> Bbox([[1, 1], [3, 7]])
		Bbox([[1.0, 1.0], [3.0, 7.0]])

		Alternatively, a Bbox can be created from the flattened points array, the
		so-called "extents" ``(xmin, ymin, xmax, ymax)``

		>>> Bbox.from_extents(1, 1, 3, 7)
		Bbox([[1.0, 1.0], [3.0, 7.0]])

		or from the "bounds" ``(xmin, ymin, width, height)``.

		>>> Bbox.from_bounds(1, 1, 2, 6)
		Bbox([[1.0, 1.0], [3.0, 7.0]])

		Create from collections of points

		The "empty" object for accumulating Bboxs is the null bbox, which is a
		stand-in for the empty set.

		>>> Bbox.null()
		Bbox([[inf, inf], [-inf, -inf]])

		Adding points to the null bbox will give you the bbox of those points.

		>>> box = Bbox.null()
		>>> box.update_from_data_xy([[1, 1]])
		>>> box
		Bbox([[1.0, 1.0], [1.0, 1.0]])
		>>> box.update_from_data_xy([[2, 3], [3, 2]], ignore=False)
		>>> box
		Bbox([[1.0, 1.0], [3.0, 3.0]])

		Setting ``ignore=True`` is equivalent to starting over from a null bbox.

		>>> box.update_from_data_xy([[1, 1]], ignore=True)
		>>> box
		Bbox([[1.0, 1.0], [1.0, 1.0]])

		.. warning::

		It is recommended to always specify ``ignore`` explicitly. If not, the
		default value of ``ignore`` can be changed at any time by code with
		access to your Bbox, for example using the method `~.Bbox.ignore`.

		Properties of the ``null`` bbox

		.. note::

		The current behavior of `Bbox.null()` may be surprising as it does
		not have all of the properties of the "empty set", and as such does
		not behave like a "zero" object in the mathematical sense. We may
		change that in the future (with a deprecation period).

		The null bbox is the identity for intersections

		>>> Bbox.intersection(Bbox([[1, 1], [3, 7]]), Bbox.null())
		Bbox([[1.0, 1.0], [3.0, 7.0]])

		except with itself, where it returns the full space.

		>>> Bbox.intersection(Bbox.null(), Bbox.null())
		Bbox([[-inf, -inf], [inf, inf]])

Copy link Member timhoffmApr 10, 2020 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Is this a reasonable behavior? Seems to contradict the semantics of update_from_data_xy. Copy link ContributorAuthor brunobeltranApr 10, 2020 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Yeah part of why I'm documenting this is because this behavior was very unexpected. I expected`Bbox.null()` to be the "zero" object of the intersection/union ring over the Bbox's. But it's not technically abug per se since it's not documented, so I didn't open an issue. Copy link ContributorAuthor brunobeltranApr 10, 2020• edited Loading Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. That said, I'd be happy to make a separate PR to fix this "bug", if other people also agree that it shouldn't be this way, but don't want to get bogged down talking about deprecation timelines, etc. here, would rather open a separate issue. Copy link Contributor anntzerApr 10, 2020 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. This and below clearly look like bugs, but I'm fine documenting these here and changing them later. tacaswell reacted with thumbs up emoji
		A union containing null will always return the full space (not the other
		set!)

		>>> Bbox.union([Bbox([[0, 0], [0, 0]]), Bbox.null()])
		Bbox([[-inf, -inf], [inf, inf]])
		"""

		def __init__(self, points, **kwargs):
Expand All		@@ -690,12 +766,6 @@ def __init__(self, points, **kwargs):
		----------
		points : ndarray
		A 2x2 numpy array of the form ``[[x0, y0], [x1, y1]]``.

		Notes
		-----
		If you need to create a `Bbox` object from another form
		of data, consider the static methods :meth:`unit`,
		:meth:`from_bounds` and :meth:`from_extents`.
		"""
		BboxBase.__init__(self, **kwargs)
		points = np.asarray(points, float)
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