Add support for minor ticks in 3d axes.

The actual implementation is shorter than deleting the copies of "Minor
ticks are not supported" in the various docstrings...

doc/users/next_whats_new/2019-06-25-AL.rst

@@ -0,0 +1,2 @@
+3D axes now support minor ticks
+```````````````````````````````

lib/matplotlib/axis.py

@@ -98,6 +98,7 @@ def __init__(self, axes, loc, label,
         name = self.__name__.lower()
 
         self._loc = loc
+        self._major = major
 
         if size is None:
             if major:

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -846,9 +846,6 @@ def set_zticks(self, *args, **kwargs):
         Set z-axis tick locations.
         See :meth:`matplotlib.axes.Axes.set_yticks` for more details.
 
-        .. note::
-            Minor ticks are not supported.
-
         .. versionadded:: 1.1.0
         """
         return self.zaxis.set_ticks(*args, **kwargs)
@@ -858,9 +855,6 @@ def get_zticks(self, minor=False):
         Return the z ticks as a list of locations
         See :meth:`matplotlib.axes.Axes.get_yticks` for more details.
 
-        .. note::
-            Minor ticks are not supported.
-
         .. versionadded:: 1.1.0
         """
         return self.zaxis.get_ticklocs(minor=minor)
@@ -877,10 +871,6 @@ def get_zminorticklabels(self):
         """
         Get the ztick labels as a list of Text instances
 
-        .. note::
-            Minor ticks are not supported. This function was added
-            only for completeness.
-
         .. versionadded :: 1.1.0
         """
         return self.zaxis.get_minorticklabels()
@@ -890,9 +880,6 @@ def set_zticklabels(self, *args, **kwargs):
         Set z-axis tick labels.
         See :meth:`matplotlib.axes.Axes.set_yticklabels` for more details.
 
-        .. note::
-            Minor ticks are not supported by Axes3D objects.
-
         .. versionadded:: 1.1.0
         """
         return self.zaxis.set_ticklabels(*args, **kwargs)
@@ -902,9 +889,6 @@ def get_zticklabels(self, minor=False):
         Get ztick labels as a list of Text instances.
         See :meth:`matplotlib.axes.Axes.get_yticklabels` for more details.
 
-        .. note::
-            Minor ticks are not supported.
-
         .. versionadded:: 1.1.0
         """
         return self.zaxis.get_ticklabels(minor=minor)

lib/mpl_toolkits/mplot3d/axis3d.py

@@ -73,33 +73,48 @@ def __init__(self, adir, v_intervalx, d_intervalx, axes, *args,
         # Do not depend on this existing in future releases!
         self._axinfo = self._AXINFO[adir].copy()
         if rcParams['_internal.classic_mode']:
-            self._axinfo.update(
-                {'label': {'va': 'center',
-                           'ha': 'center'},
-                 'tick': {'inward_factor': 0.2,
-                          'outward_factor': 0.1,
-                          'linewidth': rcParams['lines.linewidth']},
-                 'axisline': {'linewidth': 0.75,
-                              'color': (0, 0, 0, 1)},
-                 'grid': {'color': (0.9, 0.9, 0.9, 1),
-                          'linewidth': 1.0,
-                          'linestyle': '-'},
-                 })
+            self._axinfo.update({
+                'label': {'va': 'center', 'ha': 'center'},
+                'tick': {
+                    'inward_factor': 0.2,
+                    'outward_factor': 0.1,
+                    'linewidth': {
+                        True: rcParams['lines.linewidth'],  # major
+                        False: rcParams['lines.linewidth'],  # minor
+                    }
+                },
+                'axisline': {'linewidth': 0.75, 'color': (0, 0, 0, 1)},
+                'grid': {
+                    'color': (0.9, 0.9, 0.9, 1),
+                    'linewidth': 1.0,
+                    'linestyle': '-',
+                },
+            })
         else:
-            self._axinfo.update(
-                {'label': {'va': 'center',
-                           'ha': 'center'},
-                 'tick': {'inward_factor': 0.2,
-                          'outward_factor': 0.1,
-                          'linewidth': rcParams.get(
-                              adir + 'tick.major.width',
-                              rcParams['xtick.major.width'])},
-                 'axisline': {'linewidth': rcParams['axes.linewidth'],
-                              'color': rcParams['axes.edgecolor']},
-                 'grid': {'color': rcParams['grid.color'],
-                          'linewidth': rcParams['grid.linewidth'],
-                          'linestyle': rcParams['grid.linestyle']},
-                 })
+            self._axinfo.update({
+                'label': {'va': 'center', 'ha': 'center'},
+                'tick': {
+                    'inward_factor': 0.2,
+                    'outward_factor': 0.1,
+                    'linewidth': {
+                        True: (  # major
+                            rcParams['xtick.major.width'] if adir in 'xz' else
+                            rcParams['ytick.major.width']),
+                        False: (  # minor
+                            rcParams['xtick.minor.width'] if adir in 'xz' else
+                            rcParams['ytick.minor.width']),
+                    }
+                },
+                'axisline': {
+                    'linewidth': rcParams['axes.linewidth'],
+                    'color': rcParams['axes.edgecolor'],
+                },
+                'grid': {
+                    'color': rcParams['grid.color'],
+                    'linewidth': rcParams['grid.linewidth'],
+                    'linestyle': rcParams['grid.linestyle'],
+                },
+            })
 
         maxis.XAxis.__init__(self, axes, *args, **kwargs)
 
@@ -140,11 +155,17 @@ def get_tick_positions(self):
     def get_major_ticks(self, numticks=None):
         ticks = maxis.XAxis.get_major_ticks(self, numticks)
         for t in ticks:
-            t.tick1line.set_transform(self.axes.transData)
-            t.tick2line.set_transform(self.axes.transData)
-            t.gridline.set_transform(self.axes.transData)
-            t.label1.set_transform(self.axes.transData)
-            t.label2.set_transform(self.axes.transData)
+            for obj in [
+                    t.tick1line, t.tick2line, t.gridline, t.label1, t.label2]:
+                obj.set_transform(self.axes.transData)
+        return ticks
+
+    def get_minor_ticks(self, numticks=None):
+        ticks = maxis.XAxis.get_minor_ticks(self, numticks)
+        for t in ticks:
+            for obj in [
+                    t.tick1line, t.tick2line, t.gridline, t.label1, t.label2]:
+                obj.set_transform(self.axes.transData)
         return ticks
 
     def set_pane_pos(self, xys):
@@ -403,7 +424,8 @@ def draw(self, renderer):
                                                renderer.M)
 
             tick_update_position(tick, (x1, x2), (y1, y2), (lx, ly))
-            tick.tick1line.set_linewidth(info['tick']['linewidth'])
+            tick.tick1line.set_linewidth(
+                info['tick']['linewidth'][tick._major])
             tick.draw(renderer)
 
         renderer.close_group('axis3d')

lib/mpl_toolkits/tests/test_mplot3d.py

@@ -942,3 +942,14 @@ def get_formatters(ax, names):
         for fmt in get_formatters(row[4], names):
             fmt.set_useMathText(
                 not mpl.rcParams["axes.formatter.use_mathtext"])
+
+
+@image_comparison(["minor_ticks.png"], style="default")
+def test_minor_ticks():
+    ax = plt.figure().add_subplot(projection="3d")
+    ax.set_xticks([0.25], minor=True)
+    ax.set_xticklabels(["quarter"], minor=True)
+    ax.set_yticks([0.33], minor=True)
+    ax.set_yticklabels(["third"], minor=True)
+    ax.set_zticks([0.50], minor=True)
+    ax.set_zticklabels(["half"], minor=True)