test_figure.py

from contextlib import nullcontext
from datetime import datetime
import io
from pathlib import Path
import platform
from types import SimpleNamespace
import warnings

import matplotlib as mpl
from matplotlib import cbook, rcParams
from matplotlib.testing.decorators import image_comparison, check_figures_equal
from matplotlib.axes import Axes
from matplotlib.figure import Figure
from matplotlib.ticker import AutoMinorLocator, FixedFormatter, ScalarFormatter
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import matplotlib.gridspec as gridspec
import numpy as np
import pytest


@image_comparison(['figure_align_labels'], extensions=['png', 'svg'],
                  tol=0 if platform.machine() == 'x86_64' else 0.01)
def test_align_labels():
    fig = plt.figure(tight_layout=True)
    gs = gridspec.GridSpec(3, 3)

    ax = fig.add_subplot(gs[0, :2])
    ax.plot(np.arange(0, 1e6, 1000))
    ax.set_ylabel('Ylabel0 0')
    ax = fig.add_subplot(gs[0, -1])
    ax.plot(np.arange(0, 1e4, 100))

    for i in range(3):
        ax = fig.add_subplot(gs[1, i])
        ax.set_ylabel('YLabel1 %d' % i)
        ax.set_xlabel('XLabel1 %d' % i)
        if i in [0, 2]:
            ax.xaxis.set_label_position("top")
            ax.xaxis.tick_top()
        if i == 0:
            for tick in ax.get_xticklabels():
                tick.set_rotation(90)
        if i == 2:
            ax.yaxis.set_label_position("right")
            ax.yaxis.tick_right()

    for i in range(3):
        ax = fig.add_subplot(gs[2, i])
        ax.set_xlabel(f'XLabel2 {i}')
        ax.set_ylabel(f'YLabel2 {i}')

        if i == 2:
            ax.plot(np.arange(0, 1e4, 10))
            ax.yaxis.set_label_position("right")
            ax.yaxis.tick_right()
            for tick in ax.get_xticklabels():
                tick.set_rotation(90)

    fig.align_labels()


def test_figure_label():
    # pyplot figure creation, selection, and closing with label/number/instance
    plt.close('all')
    fig_today = plt.figure('today')
    plt.figure(3)
    plt.figure('tomorrow')
    plt.figure()
    plt.figure(0)
    plt.figure(1)
    plt.figure(3)
    assert plt.get_fignums() == [0, 1, 3, 4, 5]
    assert plt.get_figlabels() == ['', 'today', '', 'tomorrow', '']
    plt.close(10)
    plt.close()
    plt.close(5)
    plt.close('tomorrow')
    assert plt.get_fignums() == [0, 1]
    assert plt.get_figlabels() == ['', 'today']
    plt.figure(fig_today)
    assert plt.gcf() == fig_today
    with pytest.raises(ValueError):
        plt.figure(Figure())


def test_fignum_exists():
    # pyplot figure creation, selection and closing with fignum_exists
    plt.figure('one')
    plt.figure(2)
    plt.figure('three')
    plt.figure()
    assert plt.fignum_exists('one')
    assert plt.fignum_exists(2)
    assert plt.fignum_exists('three')
    assert plt.fignum_exists(4)
    plt.close('one')
    plt.close(4)
    assert not plt.fignum_exists('one')
    assert not plt.fignum_exists(4)


def test_clf_keyword():
    # test if existing figure is cleared with figure() and subplots()
    text1 = 'A fancy plot'
    text2 = 'Really fancy!'

    fig0 = plt.figure(num=1)
    fig0.suptitle(text1)
    assert [t.get_text() for t in fig0.texts] == [text1]

    fig1 = plt.figure(num=1, clear=False)
    fig1.text(0.5, 0.5, text2)
    assert fig0 is fig1
    assert [t.get_text() for t in fig1.texts] == [text1, text2]

    fig2, ax2 = plt.subplots(2, 1, num=1, clear=True)
    assert fig0 is fig2
    assert [t.get_text() for t in fig2.texts] == []


@image_comparison(['figure_today'])
def test_figure():
    # named figure support
    fig = plt.figure('today')
    ax = fig.add_subplot()
    ax.set_title(fig.get_label())
    ax.plot(np.arange(5))
    # plot red line in a different figure.
    plt.figure('tomorrow')
    plt.plot([0, 1], [1, 0], 'r')
    # Return to the original; make sure the red line is not there.
    plt.figure('today')
    plt.close('tomorrow')


@image_comparison(['figure_legend'])
def test_figure_legend():
    fig, axs = plt.subplots(2)
    axs[0].plot([0, 1], [1, 0], label='x', color='g')
    axs[0].plot([0, 1], [0, 1], label='y', color='r')
    axs[0].plot([0, 1], [0.5, 0.5], label='y', color='k')

    axs[1].plot([0, 1], [1, 0], label='_y', color='r')
    axs[1].plot([0, 1], [0, 1], label='z', color='b')
    fig.legend()


def test_gca():
    fig = plt.figure()

    with pytest.warns(UserWarning):
        # empty call to add_axes() will throw deprecation warning
        assert fig.add_axes() is None

    ax0 = fig.add_axes([0, 0, 1, 1])
    assert fig.gca(projection='rectilinear') is ax0
    assert fig.gca() is ax0

    ax1 = fig.add_axes(rect=[0.1, 0.1, 0.8, 0.8])
    assert fig.gca(projection='rectilinear') is ax1
    assert fig.gca() is ax1

    ax2 = fig.add_subplot(121, projection='polar')
    assert fig.gca() is ax2
    assert fig.gca(polar=True) is ax2

    ax3 = fig.add_subplot(122)
    assert fig.gca() is ax3

    # the final request for a polar axes will end up creating one
    # with a spec of 111.
    with pytest.warns(UserWarning):
        # Changing the projection will throw a warning
        assert fig.gca(polar=True) is not ax3
    assert fig.gca(polar=True) is not ax2
    assert fig.gca().get_subplotspec().get_geometry() == (1, 1, 0, 0)

    fig.sca(ax1)
    assert fig.gca(projection='rectilinear') is ax1
    assert fig.gca() is ax1


def test_add_subplot_subclass():
    fig = plt.figure()
    fig.add_subplot(axes_class=Axes)
    with pytest.raises(ValueError):
        fig.add_subplot(axes_class=Axes, projection="3d")
    with pytest.raises(ValueError):
        fig.add_subplot(axes_class=Axes, polar=True)
    with pytest.raises(ValueError):
        fig.add_subplot(projection="3d", polar=True)
    with pytest.raises(TypeError):
        fig.add_subplot(projection=42)


def test_add_subplot_invalid():
    fig = plt.figure()
    with pytest.raises(ValueError,
                       match='Number of columns must be a positive integer'):
        fig.add_subplot(2, 0, 1)
    with pytest.raises(ValueError,
                       match='Number of rows must be a positive integer'):
        fig.add_subplot(0, 2, 1)
    with pytest.raises(ValueError, match='num must be 1 <= num <= 4'):
        fig.add_subplot(2, 2, 0)
    with pytest.raises(ValueError, match='num must be 1 <= num <= 4'):
        fig.add_subplot(2, 2, 5)

    with pytest.raises(ValueError, match='must be a three-digit integer'):
        fig.add_subplot(42)
    with pytest.raises(ValueError, match='must be a three-digit integer'):
        fig.add_subplot(1000)

    with pytest.raises(TypeError, match='takes 1 or 3 positional arguments '
                                        'but 2 were given'):
        fig.add_subplot(2, 2)
    with pytest.raises(TypeError, match='takes 1 or 3 positional arguments '
                                        'but 4 were given'):
        fig.add_subplot(1, 2, 3, 4)
    with pytest.warns(cbook.MatplotlibDeprecationWarning,
                      match='Passing non-integers as three-element position '
                            'specification is deprecated'):
        fig.add_subplot('2', 2, 1)
    with pytest.warns(cbook.MatplotlibDeprecationWarning,
                      match='Passing non-integers as three-element position '
                            'specification is deprecated'):
        fig.add_subplot(2.0, 2, 1)


@image_comparison(['figure_suptitle'])
def test_suptitle():
    fig, _ = plt.subplots()
    fig.suptitle('hello', color='r')
    fig.suptitle('title', color='g', rotation='30')


def test_suptitle_fontproperties():
    fig, ax = plt.subplots()
    fps = mpl.font_manager.FontProperties(size='large', weight='bold')
    txt = fig.suptitle('fontprops title', fontproperties=fps)
    assert txt.get_fontsize() == fps.get_size_in_points()
    assert txt.get_weight() == fps.get_weight()


@image_comparison(['alpha_background'],
                  # only test png and svg. The PDF output appears correct,
                  # but Ghostscript does not preserve the background color.
                  extensions=['png', 'svg'],
                  savefig_kwarg={'facecolor': (0, 1, 0.4),
                                 'edgecolor': 'none'})
def test_alpha():
    # We want an image which has a background color and an alpha of 0.4.
    fig = plt.figure(figsize=[2, 1])
    fig.set_facecolor((0, 1, 0.4))
    fig.patch.set_alpha(0.4)
    fig.patches.append(mpl.patches.CirclePolygon(
        [20, 20], radius=15, alpha=0.6, facecolor='red'))


def test_too_many_figures():
    with pytest.warns(RuntimeWarning):
        for i in range(rcParams['figure.max_open_warning'] + 1):
            plt.figure()


def test_iterability_axes_argument():

    # This is a regression test for matplotlib/matplotlib#3196. If one of the
    # arguments returned by _as_mpl_axes defines __getitem__ but is not
    # iterable, this would raise an exception. This is because we check
    # whether the arguments are iterable, and if so we try and convert them
    # to a tuple. However, the ``iterable`` function returns True if
    # __getitem__ is present, but some classes can define __getitem__ without
    # being iterable. The tuple conversion is now done in a try...except in
    # case it fails.

    class MyAxes(Axes):
        def __init__(self, *args, myclass=None, **kwargs):
            return Axes.__init__(self, *args, **kwargs)

    class MyClass:

        def __getitem__(self, item):
            if item != 'a':
                raise ValueError("item should be a")

        def _as_mpl_axes(self):
            return MyAxes, {'myclass': self}

    fig = plt.figure()
    fig.add_subplot(1, 1, 1, projection=MyClass())
    plt.close(fig)


def test_set_fig_size():
    fig = plt.figure()

    # check figwidth
    fig.set_figwidth(5)
    assert fig.get_figwidth() == 5

    # check figheight
    fig.set_figheight(1)
    assert fig.get_figheight() == 1

    # check using set_size_inches
    fig.set_size_inches(2, 4)
    assert fig.get_figwidth() == 2
    assert fig.get_figheight() == 4

    # check using tuple to first argument
    fig.set_size_inches((1, 3))
    assert fig.get_figwidth() == 1
    assert fig.get_figheight() == 3


def test_axes_remove():
    fig, axs = plt.subplots(2, 2)
    axs[-1, -1].remove()
    for ax in axs.ravel()[:-1]:
        assert ax in fig.axes
    assert axs[-1, -1] not in fig.axes
    assert len(fig.axes) == 3


def test_figaspect():
    w, h = plt.figaspect(np.float64(2) / np.float64(1))
    assert h / w == 2
    w, h = plt.figaspect(2)
    assert h / w == 2
    w, h = plt.figaspect(np.zeros((1, 2)))
    assert h / w == 0.5
    w, h = plt.figaspect(np.zeros((2, 2)))
    assert h / w == 1


@pytest.mark.parametrize('which', [None, 'both', 'major', 'minor'])
def test_autofmt_xdate(which):
    date = ['3 Jan 2013', '4 Jan 2013', '5 Jan 2013', '6 Jan 2013',
            '7 Jan 2013', '8 Jan 2013', '9 Jan 2013', '10 Jan 2013',
            '11 Jan 2013', '12 Jan 2013', '13 Jan 2013', '14 Jan 2013']

    time = ['16:44:00', '16:45:00', '16:46:00', '16:47:00', '16:48:00',
            '16:49:00', '16:51:00', '16:52:00', '16:53:00', '16:55:00',
            '16:56:00', '16:57:00']

    angle = 60
    minors = [1, 2, 3, 4, 5, 6, 7]

    x = mdates.datestr2num(date)
    y = mdates.datestr2num(time)

    fig, ax = plt.subplots()

    ax.plot(x, y)
    ax.yaxis_date()
    ax.xaxis_date()

    ax.xaxis.set_minor_locator(AutoMinorLocator(2))
    with warnings.catch_warnings():
        warnings.filterwarnings(
            'ignore',
            'FixedFormatter should only be used together with FixedLocator')
        ax.xaxis.set_minor_formatter(FixedFormatter(minors))

    with (pytest.warns(mpl.MatplotlibDeprecationWarning) if which is None else
          nullcontext()):
        fig.autofmt_xdate(0.2, angle, 'right', which)

    if which in ('both', 'major', None):
        for label in fig.axes[0].get_xticklabels(False, 'major'):
            assert int(label.get_rotation()) == angle

    if which in ('both', 'minor'):
        for label in fig.axes[0].get_xticklabels(True, 'minor'):
            assert int(label.get_rotation()) == angle


@pytest.mark.style('default')
def test_change_dpi():
    fig = plt.figure(figsize=(4, 4))
    fig.canvas.draw()
    assert fig.canvas.renderer.height == 400
    assert fig.canvas.renderer.width == 400
    fig.dpi = 50
    fig.canvas.draw()
    assert fig.canvas.renderer.height == 200
    assert fig.canvas.renderer.width == 200


@pytest.mark.parametrize('width, height', [
    (1, np.nan),
    (-1, 1),
    (np.inf, 1)
])
def test_invalid_figure_size(width, height):
    with pytest.raises(ValueError):
        plt.figure(figsize=(width, height))

    fig = plt.figure()
    with pytest.raises(ValueError):
        fig.set_size_inches(width, height)


def test_invalid_figure_add_axes():
    fig = plt.figure()
    with pytest.raises(ValueError):
        fig.add_axes((.1, .1, .5, np.nan))

    with pytest.raises(TypeError, match="multiple values for argument 'rect'"):
        fig.add_axes([0, 0, 1, 1], rect=[0, 0, 1, 1])


def test_subplots_shareax_loglabels():
    fig, axs = plt.subplots(2, 2, sharex=True, sharey=True, squeeze=False)
    for ax in axs.flat:
        ax.plot([10, 20, 30], [10, 20, 30])

    ax.set_yscale("log")
    ax.set_xscale("log")

    for ax in axs[0, :]:
        assert 0 == len(ax.xaxis.get_ticklabels(which='both'))

    for ax in axs[1, :]:
        assert 0 < len(ax.xaxis.get_ticklabels(which='both'))

    for ax in axs[:, 1]:
        assert 0 == len(ax.yaxis.get_ticklabels(which='both'))

    for ax in axs[:, 0]:
        assert 0 < len(ax.yaxis.get_ticklabels(which='both'))


def test_savefig():
    fig = plt.figure()
    msg = r"savefig\(\) takes 2 positional arguments but 3 were given"
    with pytest.raises(TypeError, match=msg):
        fig.savefig("fname1.png", "fname2.png")


def test_savefig_warns():
    fig = plt.figure()
    msg = r'savefig\(\) got unexpected keyword argument "non_existent_kwarg"'
    for format in ['png', 'pdf', 'svg', 'tif', 'jpg']:
        with pytest.warns(cbook.MatplotlibDeprecationWarning, match=msg):
            fig.savefig(io.BytesIO(), format=format, non_existent_kwarg=True)


def test_savefig_backend():
    fig = plt.figure()
    # Intentionally use an invalid module name.
    with pytest.raises(ModuleNotFoundError, match="No module named '@absent'"):
        fig.savefig("test", backend="module://@absent")
    with pytest.raises(ValueError,
                       match="The 'pdf' backend does not support png output"):
        fig.savefig("test.png", backend="pdf")


def test_figure_repr():
    fig = plt.figure(figsize=(10, 20), dpi=10)
    assert repr(fig) == "<Figure size 100x200 with 0 Axes>"


def test_warn_cl_plus_tl():
    fig, ax = plt.subplots(constrained_layout=True)
    with pytest.warns(UserWarning):
        # this should warn,
        fig.subplots_adjust(top=0.8)
    assert not(fig.get_constrained_layout())


@check_figures_equal(extensions=["png", "pdf"])
def test_add_artist(fig_test, fig_ref):
    fig_test.set_dpi(100)
    fig_ref.set_dpi(100)

    fig_test.subplots()
    l1 = plt.Line2D([.2, .7], [.7, .7], gid='l1')
    l2 = plt.Line2D([.2, .7], [.8, .8], gid='l2')
    r1 = plt.Circle((20, 20), 100, transform=None, gid='C1')
    r2 = plt.Circle((.7, .5), .05, gid='C2')
    r3 = plt.Circle((4.5, .8), .55, transform=fig_test.dpi_scale_trans,
                    facecolor='crimson', gid='C3')
    for a in [l1, l2, r1, r2, r3]:
        fig_test.add_artist(a)
    l2.remove()

    ax2 = fig_ref.subplots()
    l1 = plt.Line2D([.2, .7], [.7, .7], transform=fig_ref.transFigure,
                    gid='l1', zorder=21)
    r1 = plt.Circle((20, 20), 100, transform=None, clip_on=False, zorder=20,
                    gid='C1')
    r2 = plt.Circle((.7, .5), .05, transform=fig_ref.transFigure, gid='C2',
                    zorder=20)
    r3 = plt.Circle((4.5, .8), .55, transform=fig_ref.dpi_scale_trans,
                    facecolor='crimson', clip_on=False, zorder=20, gid='C3')
    for a in [l1, r1, r2, r3]:
        ax2.add_artist(a)


@pytest.mark.parametrize("fmt", ["png", "pdf", "ps", "eps", "svg"])
def test_fspath(fmt, tmpdir):
    out = Path(tmpdir, "test.{}".format(fmt))
    plt.savefig(out)
    with out.open("rb") as file:
        # All the supported formats include the format name (case-insensitive)
        # in the first 100 bytes.
        assert fmt.encode("ascii") in file.read(100).lower()


def test_tightbbox():
    fig, ax = plt.subplots()
    ax.set_xlim(0, 1)
    t = ax.text(1., 0.5, 'This dangles over end')
    renderer = fig.canvas.get_renderer()
    x1Nom0 = 9.035  # inches
    assert abs(t.get_tightbbox(renderer).x1 - x1Nom0 * fig.dpi) < 2
    assert abs(ax.get_tightbbox(renderer).x1 - x1Nom0 * fig.dpi) < 2
    assert abs(fig.get_tightbbox(renderer).x1 - x1Nom0) < 0.05
    assert abs(fig.get_tightbbox(renderer).x0 - 0.679) < 0.05
    # now exclude t from the tight bbox so now the bbox is quite a bit
    # smaller
    t.set_in_layout(False)
    x1Nom = 7.333
    assert abs(ax.get_tightbbox(renderer).x1 - x1Nom * fig.dpi) < 2
    assert abs(fig.get_tightbbox(renderer).x1 - x1Nom) < 0.05

    t.set_in_layout(True)
    x1Nom = 7.333
    assert abs(ax.get_tightbbox(renderer).x1 - x1Nom0 * fig.dpi) < 2
    # test bbox_extra_artists method...
    assert abs(ax.get_tightbbox(renderer, bbox_extra_artists=[]).x1
               - x1Nom * fig.dpi) < 2


def test_axes_removal():
    # Check that units can set the formatter after an Axes removal
    fig, axs = plt.subplots(1, 2, sharex=True)
    axs[1].remove()
    axs[0].plot([datetime(2000, 1, 1), datetime(2000, 2, 1)], [0, 1])
    assert isinstance(axs[0].xaxis.get_major_formatter(),
                      mdates.AutoDateFormatter)

    # Check that manually setting the formatter, then removing Axes keeps
    # the set formatter.
    fig, axs = plt.subplots(1, 2, sharex=True)
    axs[1].xaxis.set_major_formatter(ScalarFormatter())
    axs[1].remove()
    axs[0].plot([datetime(2000, 1, 1), datetime(2000, 2, 1)], [0, 1])
    assert isinstance(axs[0].xaxis.get_major_formatter(),
                      ScalarFormatter)


def test_removed_axis():
    # Simple smoke test to make sure removing a shared axis works
    fig, axs = plt.subplots(2, sharex=True)
    axs[0].remove()
    fig.canvas.draw()


@pytest.mark.style('mpl20')
def test_picking_does_not_stale():
    fig, ax = plt.subplots()
    col = ax.scatter([0], [0], [1000], picker=True)
    fig.canvas.draw()
    assert not fig.stale

    mouse_event = SimpleNamespace(x=ax.bbox.x0 + ax.bbox.width / 2,
                                  y=ax.bbox.y0 + ax.bbox.height / 2,
                                  inaxes=ax, guiEvent=None)
    fig.pick(mouse_event)
    assert not fig.stale


def test_add_subplot_twotuple():
    fig = plt.figure()
    ax1 = fig.add_subplot(3, 2, (3, 5))
    assert ax1.get_subplotspec().rowspan == range(1, 3)
    assert ax1.get_subplotspec().colspan == range(0, 1)
    ax2 = fig.add_subplot(3, 2, (4, 6))
    assert ax2.get_subplotspec().rowspan == range(1, 3)
    assert ax2.get_subplotspec().colspan == range(1, 2)
    ax3 = fig.add_subplot(3, 2, (3, 6))
    assert ax3.get_subplotspec().rowspan == range(1, 3)
    assert ax3.get_subplotspec().colspan == range(0, 2)
    ax4 = fig.add_subplot(3, 2, (4, 5))
    assert ax4.get_subplotspec().rowspan == range(1, 3)
    assert ax4.get_subplotspec().colspan == range(0, 2)
    with pytest.raises(IndexError):
        fig.add_subplot(3, 2, (6, 3))


@image_comparison(['tightbbox_box_aspect.svg'], style='mpl20',
                  savefig_kwarg={'bbox_inches': 'tight',
                                 'facecolor': 'teal'},
                  remove_text=True)
def test_tightbbox_box_aspect():
    fig = plt.figure()
    gs = fig.add_gridspec(1, 2)
    ax1 = fig.add_subplot(gs[0, 0])
    ax2 = fig.add_subplot(gs[0, 1], projection='3d')
    ax1.set_box_aspect(.5)
    ax2.set_box_aspect((2, 1, 1))


@check_figures_equal(extensions=["svg", "pdf", "eps", "png"])
def test_animated_with_canvas_change(fig_test, fig_ref):
    ax_ref = fig_ref.subplots()
    ax_ref.plot(range(5))

    ax_test = fig_test.subplots()
    ax_test.plot(range(5), animated=True)


class TestSubplotMosaic:
    @check_figures_equal(extensions=["png"])
    @pytest.mark.parametrize(
        "x", [[["A", "A", "B"], ["C", "D", "B"]], [[1, 1, 2], [3, 4, 2]]]
    )
    def test_basic(self, fig_test, fig_ref, x):
        grid_axes = fig_test.subplot_mosaic(x)

        for k, ax in grid_axes.items():
            ax.set_title(k)

        labels = sorted(np.unique(x))

        assert len(labels) == len(grid_axes)

        gs = fig_ref.add_gridspec(2, 3)
        axA = fig_ref.add_subplot(gs[:1, :2])
        axA.set_title(labels[0])

        axB = fig_ref.add_subplot(gs[:, 2])
        axB.set_title(labels[1])

        axC = fig_ref.add_subplot(gs[1, 0])
        axC.set_title(labels[2])

        axD = fig_ref.add_subplot(gs[1, 1])
        axD.set_title(labels[3])

    @check_figures_equal(extensions=["png"])
    def test_all_nested(self, fig_test, fig_ref):
        x = [["A", "B"], ["C", "D"]]
        y = [["E", "F"], ["G", "H"]]

        fig_ref.set_constrained_layout(True)
        fig_test.set_constrained_layout(True)

        grid_axes = fig_test.subplot_mosaic([[x, y]])
        for ax in grid_axes.values():
            ax.set_title(ax.get_label())

        gs = fig_ref.add_gridspec(1, 2)
        gs_left = gs[0, 0].subgridspec(2, 2)
        for j, r in enumerate(x):
            for k, label in enumerate(r):
                fig_ref.add_subplot(gs_left[j, k]).set_title(label)

        gs_right = gs[0, 1].subgridspec(2, 2)
        for j, r in enumerate(y):
            for k, label in enumerate(r):
                fig_ref.add_subplot(gs_right[j, k]).set_title(label)

    @check_figures_equal(extensions=["png"])
    def test_nested(self, fig_test, fig_ref):

        fig_ref.set_constrained_layout(True)
        fig_test.set_constrained_layout(True)

        x = [["A", "B"], ["C", "D"]]

        y = [["F"], [x]]

        grid_axes = fig_test.subplot_mosaic(y)

        for k, ax in grid_axes.items():
            ax.set_title(k)

        gs = fig_ref.add_gridspec(2, 1)

        gs_n = gs[1, 0].subgridspec(2, 2)

        axA = fig_ref.add_subplot(gs_n[0, 0])
        axA.set_title("A")

        axB = fig_ref.add_subplot(gs_n[0, 1])
        axB.set_title("B")

        axC = fig_ref.add_subplot(gs_n[1, 0])
        axC.set_title("C")

        axD = fig_ref.add_subplot(gs_n[1, 1])
        axD.set_title("D")

        axF = fig_ref.add_subplot(gs[0, 0])
        axF.set_title("F")

    @check_figures_equal(extensions=["png"])
    def test_nested_tuple(self, fig_test, fig_ref):
        x = [["A", "B", "B"], ["C", "C", "D"]]
        xt = (("A", "B", "B"), ("C", "C", "D"))

        fig_ref.subplot_mosaic([["F"], [x]])
        fig_test.subplot_mosaic([["F"], [xt]])

    @check_figures_equal(extensions=["png"])
    @pytest.mark.parametrize(
        "x, empty_sentinel",
        [
            ([["A", None], [None, "B"]], None),
            ([["A", "."], [".", "B"]], "SKIP"),
            ([["A", 0], [0, "B"]], 0),
            ([[1, None], [None, 2]], None),
            ([[1, "."], [".", 2]], "SKIP"),
            ([[1, 0], [0, 2]], 0),
        ],
    )
    def test_empty(self, fig_test, fig_ref, x, empty_sentinel):
        if empty_sentinel != "SKIP":
            kwargs = {"empty_sentinel": empty_sentinel}
        else:
            kwargs = {}
        grid_axes = fig_test.subplot_mosaic(x, **kwargs)

        for k, ax in grid_axes.items():
            ax.set_title(k)

        labels = sorted(
            {name for row in x for name in row} - {empty_sentinel, "."}
        )

        assert len(labels) == len(grid_axes)

        gs = fig_ref.add_gridspec(2, 2)
        axA = fig_ref.add_subplot(gs[0, 0])
        axA.set_title(labels[0])

        axB = fig_ref.add_subplot(gs[1, 1])
        axB.set_title(labels[1])

    def test_fail_list_of_str(self):
        with pytest.raises(ValueError, match='must be 2D'):
            plt.subplot_mosaic(['foo', 'bar'])

    @check_figures_equal(extensions=["png"])
    @pytest.mark.parametrize("subplot_kw", [{}, {"projection": "polar"}, None])
    def test_subplot_kw(self, fig_test, fig_ref, subplot_kw):
        x = [[1, 2]]
        grid_axes = fig_test.subplot_mosaic(x, subplot_kw=subplot_kw)
        subplot_kw = subplot_kw or {}

        gs = fig_ref.add_gridspec(1, 2)
        axA = fig_ref.add_subplot(gs[0, 0], **subplot_kw)

        axB = fig_ref.add_subplot(gs[0, 1], **subplot_kw)

    def test_string_parser(self):
        normalize = Figure._normalize_grid_string
        assert normalize('ABC') == [['A', 'B', 'C']]
        assert normalize('AB;CC') == [['A', 'B'], ['C', 'C']]
        assert normalize('AB;CC;DE') == [['A', 'B'], ['C', 'C'], ['D', 'E']]
        assert normalize("""
                         ABC
                         """) == [['A', 'B', 'C']]
        assert normalize("""
                         AB
                         CC
                         """) == [['A', 'B'], ['C', 'C']]
        assert normalize("""
                         AB
                         CC
                         DE
                         """) == [['A', 'B'], ['C', 'C'], ['D', 'E']]

    @check_figures_equal(extensions=["png"])
    @pytest.mark.parametrize("str_pattern",
                             ["AAA\nBBB", "\nAAA\nBBB\n", "ABC\nDEF"]
                             )
    def test_single_str_input(self, fig_test, fig_ref, str_pattern):
        grid_axes = fig_test.subplot_mosaic(str_pattern)

        grid_axes = fig_ref.subplot_mosaic(
            [list(ln) for ln in str_pattern.strip().split("\n")]
        )

    @pytest.mark.parametrize(
        "x,match",
        [
            (
                [["A", "."], [".", "A"]],
                (
                    "(?m)we found that the label .A. specifies a "
                    + "non-rectangular or non-contiguous area."
                ),
            ),
            (
                [["A", "B"], [None, [["A", "B"], ["C", "D"]]]],
                "There are duplicate keys .* between the outer layout",
            ),
            ("AAA\nc\nBBB", "All of the rows must be the same length"),
            (
                [["A", [["B", "C"], ["D"]]], ["E", "E"]],
                "All of the rows must be the same length",
            ),
        ],
    )
    def test_fail(self, x, match):
        fig = plt.figure()
        with pytest.raises(ValueError, match=match):
            fig.subplot_mosaic(x)

    @check_figures_equal(extensions=["png"])
    def test_hashable_keys(self, fig_test, fig_ref):
        fig_test.subplot_mosaic([[object(), object()]])
        fig_ref.subplot_mosaic([["A", "B"]])


def test_reused_gridspec():
    """Test that these all use the same gridspec"""
    fig = plt.figure()
    ax1 = fig.add_subplot(3, 2, (3, 5))
    ax2 = fig.add_subplot(3, 2, 4)
    ax3 = plt.subplot2grid((3, 2), (2, 1), colspan=2, fig=fig)

    gs1 = ax1.get_subplotspec().get_gridspec()
    gs2 = ax2.get_subplotspec().get_gridspec()
    gs3 = ax3.get_subplotspec().get_gridspec()

    assert gs1 == gs2
    assert gs1 == gs3


@image_comparison(['test_subfigure.png'], style='mpl20',
                  savefig_kwarg={'facecolor': 'teal'},
                  remove_text=False)
def test_subfigure():
    np.random.seed(19680801)
    fig = plt.figure(constrained_layout=True)
    sub = fig.subfigures(1, 2)

    axs = sub[0].subplots(2, 2)
    for ax in axs.flat:
        pc = ax.pcolormesh(np.random.randn(30, 30), vmin=-2, vmax=2)
    sub[0].colorbar(pc, ax=axs)
    sub[0].suptitle('Left Side')

    axs = sub[1].subplots(1, 3)
    for ax in axs.flat:
        pc = ax.pcolormesh(np.random.randn(30, 30), vmin=-2, vmax=2)
    sub[1].colorbar(pc, ax=axs, location='bottom')
    sub[1].suptitle('Right Side')

    fig.suptitle('Figure suptitle', fontsize='xx-large')


@image_comparison(['test_subfigure_ss.png'], style='mpl20',
                  savefig_kwarg={'facecolor': 'teal'},
                  remove_text=False)
def test_subfigure_ss():
    # test assigning the subfigure via subplotspec
    np.random.seed(19680801)
    fig = plt.figure(constrained_layout=True)
    gs = fig.add_gridspec(1, 2)

    sub = fig.add_subfigure(gs[0], facecolor='pink')

    axs = sub.subplots(2, 2)
    for ax in axs.flat:
        pc = ax.pcolormesh(np.random.randn(30, 30), vmin=-2, vmax=2)
    sub.colorbar(pc, ax=axs)
    sub.suptitle('Left Side')

    ax = fig.add_subplot(gs[1])
    ax.plot(np.arange(20))
    ax.set_title('Axes')

    fig.suptitle('Figure suptitle', fontsize='xx-large')


@image_comparison(['test_subfigure_double.png'], style='mpl20',
                  savefig_kwarg={'facecolor': 'teal'},
                  remove_text=False)
def test_subfigure_double():
    # test assigning the subfigure via subplotspec
    np.random.seed(19680801)

    fig = plt.figure(constrained_layout=True, figsize=(10, 8))

    fig.suptitle('fig')

    subfigs = fig.subfigures(1, 2, wspace=0.07)

    subfigs[0].set_facecolor('coral')
    subfigs[0].suptitle('subfigs[0]')

    subfigs[1].set_facecolor('coral')
    subfigs[1].suptitle('subfigs[1]')

    subfigsnest = subfigs[0].subfigures(2, 1, height_ratios=[1, 1.4])
    subfigsnest[0].suptitle('subfigsnest[0]')
    subfigsnest[0].set_facecolor('r')
    axsnest0 = subfigsnest[0].subplots(1, 2, sharey=True)
    for ax in axsnest0:
        fontsize = 12
        pc = ax.pcolormesh(np.random.randn(30, 30), vmin=-2.5, vmax=2.5)
        ax.set_xlabel('x-label', fontsize=fontsize)
        ax.set_ylabel('y-label', fontsize=fontsize)
        ax.set_title('Title', fontsize=fontsize)

    subfigsnest[0].colorbar(pc, ax=axsnest0)

    subfigsnest[1].suptitle('subfigsnest[1]')
    subfigsnest[1].set_facecolor('g')
    axsnest1 = subfigsnest[1].subplots(3, 1, sharex=True)
    for nn, ax in enumerate(axsnest1):
        ax.set_ylabel(f'ylabel{nn}')
    subfigsnest[1].supxlabel('supxlabel')
    subfigsnest[1].supylabel('supylabel')

    axsRight = subfigs[1].subplots(2, 2)