Implement exact 3d plot limits

scottshambaugh · scottshambaugh · commit 0da1b6c80ff0 · 2023-08-27T05:35:47.000-06:00
Fix remaining large image diffs

Fix remaining large image diffs

Fix the rest of the tests

Fix docs error

Code review updates

Code review updates

Fix docs error

One more constant

Tweaks

Keep fixing CI errors

Docstrings

Update baseline images

More test images

Images

Test new scaling factor

Test new scaling factor

Test for exact limits

Cleanup

Tests

Update doc/users/next_whats_new/3d_axis_limits.rst

Co-authored-by: Elliott Sales de Andrade &lt;quantum.analyst@gmail.com&gt;

rebase fixes

Apply suggestions from code review

Co-authored-by: Oscar Gustafsson &lt;oscar.gustafsson@gmail.com&gt;

Code review cleanup

Merge conflicts and better comments

Merge conflicts and better comments
diff --git a/doc/api/toolkits/mplot3d/axes3d.rst b/doc/api/toolkits/mplot3d/axes3d.rst
@@ -92,12 +92,18 @@ Axis limits and direction
 
    get_zaxis
    get_xlim
+   set_xlim
    get_ylim
+   set_ylim
    get_zlim
    set_zlim
    get_w_lims
    invert_zaxis
    zaxis_inverted
+   get_xbound
+   set_xbound
+   get_ybound
+   set_ybound
    get_zbound
    set_zbound
 
diff --git a/doc/users/next_whats_new/3d_axis_limits.rst b/doc/users/next_whats_new/3d_axis_limits.rst
@@ -0,0 +1,18 @@
+Setting 3D axis limits now set the limits exactly
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Previously, setting the limits of a 3D axis would always add a small margin to
+the limits. Limits are now set exactly by default. The newly introduced rcparam
+``axes3d.automargin`` can be used to revert to the old behavior where margin is
+automatically added.
+
+.. plot::
+    :include-source: true
+    :alt: Example of the new behavior of 3D axis limits, and how setting the rcparam reverts to the old behavior.
+
+    import matplotlib.pyplot as plt
+    fig, axs = plt.subplots(1, 2, subplot_kw={'projection': '3d'})
+    plt.rcParams['axes3d.automargin'] = False  # the default in 3.9.0
+    axs[0].set(xlim=(0, 1), ylim=(0, 1), zlim=(0, 1), title='New Behavior')
+    plt.rcParams['axes3d.automargin'] = True
+    axs[1].set(xlim=(0, 1), ylim=(0, 1), zlim=(0, 1), title='Old Behavior')
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -855,13 +855,14 @@ def _get_autoscale_on(self):
     def _set_autoscale_on(self, b):
         """
         Set whether this Axis is autoscaled when drawing or by
-        `.Axes.autoscale_view`.
+        `.Axes.autoscale_view`. If b is None, then the value is not changed.
 
         Parameters
         ----------
         b : bool
         """
-        self._autoscale_on = b
+        if b is not None:
+            self._autoscale_on = b
 
     def get_children(self):
         return [self.label, self.offsetText,
@@ -1244,8 +1245,7 @@ def _set_lim(self, v0, v1, *, emit=True, auto):
         # Mark viewlims as no longer stale without triggering an autoscale.
         for ax in self._get_shared_axes():
             ax._stale_viewlims[name] = False
-        if auto is not None:
-            self._set_autoscale_on(bool(auto))
+        self._set_autoscale_on(auto)
 
         if emit:
             self.axes.callbacks.process(f"{name}lim_changed", self.axes)
@@ -1292,6 +1292,17 @@ def _update_ticks(self):
         if view_low > view_high:
             view_low, view_high = view_high, view_low
 
+        if (hasattr(self, "axes") and self.axes.name == '3d'
+                and mpl.rcParams['axes3d.automargin']):
+            # In mpl3.8, the margin was 1/48. Due to the change in automargin
+            # behavior in mpl3.9, we need to adjust this to compensate for a
+            # zoom factor of 2/48, giving us a 23/24 modifier. So the new
+            # margin is 0.019965277777777776 = 1/48*23/24.
+            margin = 0.019965277777777776
+            delta = view_high - view_low
+            view_high = view_high - delta * margin
+            view_low = view_low + delta * margin
+
         interval_t = self.get_transform().transform([view_low, view_high])
 
         ticks_to_draw = []
diff --git a/lib/matplotlib/mpl-data/matplotlibrc b/lib/matplotlib/mpl-data/matplotlibrc
@@ -425,8 +425,9 @@
 #axes.autolimit_mode: data  # If "data", use axes.xmargin and axes.ymargin as is.
                             # If "round_numbers", after application of margins, axis
                             # limits are further expanded to the nearest "round" number.
-#polaraxes.grid: True  # display grid on polar axes
-#axes3d.grid:    True  # display grid on 3D axes
+#polaraxes.grid:    True   # display grid on polar axes
+#axes3d.grid:       True   # display grid on 3D axes
+#axes3d.automargin: False  # automatically add margin when manually setting 3D axis limits
 
 #axes3d.xaxis.panecolor:    (0.95, 0.95, 0.95, 0.5)  # background pane on 3D axes
 #axes3d.yaxis.panecolor:    (0.90, 0.90, 0.90, 0.5)  # background pane on 3D axes
diff --git a/lib/matplotlib/mpl-data/stylelib/classic.mplstyle b/lib/matplotlib/mpl-data/stylelib/classic.mplstyle
@@ -223,7 +223,8 @@ axes.spines.left    : True
 axes.spines.right   : True
 axes.spines.top     : True
 polaraxes.grid      : True    # display grid on polar axes
-axes3d.grid         : True    # display grid on 3d axes
+axes3d.grid         : True    # display grid on 3D axes
+axes3d.automargin   : False   # automatically add margin when manually setting 3D axis limits
 
 date.autoformatter.year   : %Y
 date.autoformatter.month  : %b %Y
diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -1094,8 +1094,10 @@ def _convert_validator_spec(key, conv):
     "axes.ymargin": _validate_greaterthan_minushalf,  # margin added to yaxis
     "axes.zmargin": _validate_greaterthan_minushalf,  # margin added to zaxis
 
-    "polaraxes.grid": validate_bool,  # display polar grid or not
-    "axes3d.grid":    validate_bool,  # display 3d grid
+    "polaraxes.grid":    validate_bool,  # display polar grid or not
+    "axes3d.grid":       validate_bool,  # display 3d grid
+    "axes3d.automargin": validate_bool,  # automatically add margin when
+                                         # manually setting 3D axis limits
 
     "axes3d.xaxis.panecolor":    validate_color,  # 3d background pane
     "axes3d.yaxis.panecolor":    validate_color,  # 3d background pane
diff --git a/lib/matplotlib/tests/test_collections.py b/lib/matplotlib/tests/test_collections.py
@@ -401,6 +401,7 @@ def test_EllipseCollection():
 @image_comparison(['polycollection_close.png'], remove_text=True, style='mpl20')
 def test_polycollection_close():
     from mpl_toolkits.mplot3d import Axes3D  # type: ignore
+    plt.rcParams['axes3d.automargin'] = True
 
     vertsQuad = [
         [[0., 0.], [0., 1.], [1., 1.], [1., 0.]],
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -2106,6 +2106,11 @@ def _raw_ticks(self, vmin, vmax):
             steps = steps[igood]
 
         raw_step = ((_vmax - _vmin) / nbins)
+        if hasattr(self.axis, "axes") and self.axis.axes.name == '3d':
+            # Due to the change in automargin behavior in mpl3.9, we need to
+            # adjust the raw step to match the mpl3.8 appearance. The zoom
+            # factor of 2/48, gives us the 23/24 modifier.
+            raw_step = raw_step * 23/24
         large_steps = steps >= raw_step
         if mpl.rcParams['axes.autolimit_mode'] == 'round_numbers':
             # Classic round_numbers mode may require a larger step.
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
diff --git a/lib/mpl_toolkits/mplot3d/axis3d.py b/lib/mpl_toolkits/mplot3d/axis3d.py
diff --git a/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py b/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py
