matplotlib · aswarner · Mar 20, 2022 · Mar 20, 2022 · Mar 27, 2022 · Mar 27, 2022
diff --git a/examples/subplots_axes_and_figures/align_titles_demo.py b/examples/subplots_axes_and_figures/align_titles_demo.py
@@ -0,0 +1,26 @@
+"""
+===============
+Aligning Labels
-Aligning Labels
+Aligning Titles
-Aligning Labels
+Aligning Titles
+===============
+
+Aligning titles using `.Figure.align_titles`.
+
+Note that the title "Title 1" would normally be much closer to the
+figure's axis.
+"""
+import matplotlib.pyplot as plt
+fig, axs = plt.subplots(2, 2,
+                        subplot_kw={"xlabel": "x", "ylabel": "", "title": "t"})
+print(axs.shape)
+axs[0][0].imshow(plt.np.zeros((3, 5)))
+axs[0][1].imshow(plt.np.zeros((5, 3)))
+axs[1][0].imshow(plt.np.zeros((1, 2)))
+axs[1][1].imshow(plt.np.zeros((2, 1)))
+axs[0][0].set_title('t2')
+rowspan1 = axs[0][0].get_subplotspec().rowspan
+print(rowspan1, rowspan1.start, rowspan1.stop)
+rowspan2 = axs[1][1].get_subplotspec().rowspan
+print(rowspan2, rowspan2.start, rowspan2.stop)
+
+fig.align_titles()
+plt.show()
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -2950,7 +2950,7 @@ def _update_title_position(self, renderer):
             _log.debug('title position was updated manually, not adjusting')
             return
 
-        titles = (self.title, self._left_title, self._right_title)
+        titles = [self.title, self._left_title, self._right_title]
-        titles = [self.title, self._left_title, self._right_title]
+        titles = (self.title, self._left_title, self._right_title)
-        titles = [self.title, self._left_title, self._right_title]
+        titles = (self.title, self._left_title, self._right_title)
 
         for title in titles:
             x, _ = title.get_position()
@@ -3008,6 +3008,17 @@ def _update_title_position(self, renderer):
             x, _ = title.get_position()
             title.set_position((x, ymax))
 
+        # Align bboxes of grouped axes to highest in group
+        grouped_axs = self.figure._align_label_groups['title'] \
+                          .get_siblings(self)
+        bb_ymax = None
+        ax_max = None
+        for ax in grouped_axs:
+            if bb_ymax is None or ax.bbox.ymax > bb_ymax:
+                bb_ymax = ax.bbox.ymax
+                ax_max = ax
+        self.bbox = ax_max.bbox
+
     # Drawing
     @martist.allow_rasterization
     def draw(self, renderer):

diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -173,7 +173,8 @@ def __init__(self, **kwargs):
         # groupers to keep track of x and y labels we want to align.
         # see self.align_xlabels and self.align_ylabels and
         # axis._get_tick_boxes_siblings
-        self._align_label_groups = {"x": cbook.Grouper(), "y": cbook.Grouper()}
+        self._align_label_groups = {"x": cbook.Grouper(), "y": cbook.Grouper(),
+                                    "title": cbook.Grouper()}
 
         self.figure = self
         # list of child gridspecs for this figure
@@ -1241,6 +1242,60 @@ def align_xlabels(self, axs=None):
                         # grouper for groups of xlabels to align
                         self._align_label_groups['x'].join(ax, axc)
 
+    def align_titles(self, axs=None):
+        """
+        Align the titles of subplots in the same subplot column if title
+        alignment is being done automatically (i.e. the title position is
+        not manually set).
+
+        Alignment persists for draw events after this is called.
+
+        Parameters
+        ----------
+        axs : list of `~matplotlib.axes.Axes`
+            Optional list of (or ndarray) `~matplotlib.axes.Axes`
+            to align the titles.
+            Default is to align all Axes on the figure.
+
+        See Also
+        --------
+        matplotlib.figure.Figure.align_xlabels
+        matplotlib.figure.Figure.align_ylabels
+        matplotlib.figure.Figure.align_labels
+
+        Notes
+        -----
+        This assumes that ``axs`` are from the same `.GridSpec`, so that
+        their `.SubplotSpec` positions correspond to figure positions.
+
+        Examples
+        --------
+        Example with titles::
+
+            fig, axs = subplots(1, 2,
+            subplot_kw={"xlabel": "x", "ylabel": "y", "title": "t"})
+            axs[0].imshow(zeros((3, 5)))
+            axs[1].imshow(zeros((5, 3)))
+            fig.align_labels()
+            fig.align_titles()
+        """
+        if axs is None:
+            axs = self.axes
+        axs = np.ravel(axs)
+        axs = [ax for ax in axs if hasattr(ax, 'get_subplotspec')]
+        locs = ['left', 'center', 'right']
+        for ax in axs:
+            for loc in locs:
+                if ax.get_title(loc=loc):
+                    _log.debug(' Working on: %s', ax.get_title(loc=loc))
+                    rowspan = ax.get_subplotspec().rowspan
+                    for axc in axs:
+                        for loc in locs:
+                            rowspanc = axc.get_subplotspec().rowspan
+                            if rowspan.start == rowspanc.start or \
+                               rowspan.stop == rowspanc.stop:
+                                self._align_label_groups['title'].join(ax, axc)
+
     def align_ylabels(self, axs=None):
         """
         Align the ylabels of subplots in the same subplot column if label
@@ -2848,6 +2903,7 @@ def draw(self, renderer):
 
         artists = self._get_draw_artists(renderer)
         try:
+
             renderer.open_group('figure', gid=self.get_gid())
             if self.axes and self.get_layout_engine() is not None:
                 try:

diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
@@ -100,6 +100,38 @@ def test_align_labels_stray_axes():
     np.testing.assert_allclose(yn[::2], yn[1::2])
 
 
+# TODO add image comparison
+@image_comparison(['figure_align_titles'], extensions=['png', 'svg'],
+                  tol=0 if platform.machine() == 'x86_64' else 0.01)
+def test_align_titles():
+    fig, axs = plt.subplots(2, 2,
+                            subplot_kw={"xlabel": "x", "ylabel": "",
+                                        "title": "Title"})
+    axs[0][0].imshow(plt.np.zeros((5, 3)))
+    axs[0][1].imshow(plt.np.zeros((3, 5)))
+    axs[1][0].imshow(plt.np.zeros((2, 1)))
+    axs[1][1].imshow(plt.np.zeros((1, 2)))
+
+    axs[0][1].set_title('Title2', loc="left")
+
+    fig.align_titles()
+
+
+## TODO add image comparison
+@image_comparison(['figure_align_titles_param'], extensions=['png', 'svg'],
+                  tol=0 if platform.machine() == 'x86_64' else 0.01)
+def test_align_titles_param():
+    fig, axs = plt.subplots(2, 2,
+                            subplot_kw={"xlabel": "x", "ylabel": "",
+                                        "title": "t"})
+    axs[0][0].imshow(plt.np.zeros((3, 5)))
+    axs[0][1].imshow(plt.np.zeros((5, 3)))
+    axs[1][0].imshow(plt.np.zeros((2, 1)))
+    axs[1][1].imshow(plt.np.zeros((1, 2)))
+
+    fig.align_titles([axs[0][0], axs[0][1]])
+
+
 def test_figure_label():
     # pyplot figure creation, selection, and closing with label/number/instance
     plt.close('all')

diff --git a/test_align_titles.py b/test_align_titles.py
@@ -0,0 +1,18 @@
+import matplotlib as plt
+fig, axs = plt.subplots(2, 2,
+                        subplot_kw={"xlabel": "x", "ylabel": "", "title": "t"})
+print(axs.shape)
+axs[0][0].imshow(plt.zeros((3, 5)))
+axs[0][1].imshow(plt.zeros((5, 3)))
+axs[1][0].imshow(plt.zeros((1, 2)))
+axs[1][1].imshow(plt.zeros((2, 1)))
+axs[0][0].set_title('t2')
+rowspan1 = axs[0][0].get_subplotspec().rowspan
+print(rowspan1, rowspan1.start, rowspan1.stop)
+rowspan2 = axs[1][1].get_subplotspec().rowspan
+print(rowspan2, rowspan2.start, rowspan2.stop)
+
+fig.align_labels()
+fig.align_titles()
+plt.show()
+print("DONE")