Inline _init_axis_artists & _init_gridlines into clear.

clear() is the only caller of these inhernal axisartist helpers, so just
inline them there.  Note that these helpers are tightly coupled to
clear() anyways (see the note about setting gridlines clip_path).  Also,
this makes it clearer that _init_axis_artist is never called with
`axes != self` and that _init_gridlines is never called with
`grid_helper != self.get_grid_helper()`.

Also get rid of the `new_gridlines` helpers, which likewise become
inlined.

Author: anntzer

doc/api/next_api_changes/deprecations/23469-AL.rst

@@ -0,0 +1,3 @@
+``axislines.GridHelperBase.new_gridlines`` and ``axislines.Axes.new_gridlines``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+... are deprecated.

lib/mpl_toolkits/axes_grid1/mpl_axes.py

@@ -40,22 +40,20 @@ def __getitem__(self, k):
         def __call__(self, *v, **kwargs):
             return maxes.Axes.axis(self.axes, *v, **kwargs)
 
-    def _init_axis_artists(self):
-        self._axislines = self.AxisDict(self)
-        self._axislines.update(
-            bottom=SimpleAxisArtist(self.xaxis, 1, self.spines["bottom"]),
-            top=SimpleAxisArtist(self.xaxis, 2, self.spines["top"]),
-            left=SimpleAxisArtist(self.yaxis, 1, self.spines["left"]),
-            right=SimpleAxisArtist(self.yaxis, 2, self.spines["right"]))
-
     @property
     def axis(self):
         return self._axislines
 
     def clear(self):
         # docstring inherited
         super().clear()
-        self._init_axis_artists()
+        # Init axis artists.
+        self._axislines = self.AxisDict(self)
+        self._axislines.update(
+            bottom=SimpleAxisArtist(self.xaxis, 1, self.spines["bottom"]),
+            top=SimpleAxisArtist(self.xaxis, 2, self.spines["top"]),
+            left=SimpleAxisArtist(self.yaxis, 1, self.spines["left"]),
+            right=SimpleAxisArtist(self.yaxis, 2, self.spines["right"]))
 
 
 class SimpleAxisArtist(Artist):

lib/mpl_toolkits/axisartist/axislines.py

@@ -332,6 +332,7 @@ def get_gridlines(self, which, axis):
         """
         return []
 
+    @_api.deprecated("3.6")
     def new_gridlines(self, ax):
         """
         Create and return a new GridlineCollection instance.
@@ -462,25 +463,11 @@ def toggle_axisline(self, b=None):
             self.xaxis.set_visible(True)
             self.yaxis.set_visible(True)
 
-    def _init_axis_artists(self, axes=None):
-        if axes is None:
-            axes = self
-
-        self._axislines = mpl_axes.Axes.AxisDict(self)
-        new_fixed_axis = self.get_grid_helper().new_fixed_axis
-        for loc in ["bottom", "top", "left", "right"]:
-            self._axislines[loc] = new_fixed_axis(loc=loc, axes=axes,
-                                                  axis_direction=loc)
-
-        for axisline in [self._axislines["top"], self._axislines["right"]]:
-            axisline.label.set_visible(False)
-            axisline.major_ticklabels.set_visible(False)
-            axisline.minor_ticklabels.set_visible(False)
-
     @property
     def axis(self):
         return self._axislines
 
+    @_api.deprecated("3.6")
     def new_gridlines(self, grid_helper=None):
         """
         Create and return a new GridlineCollection instance.
@@ -495,21 +482,33 @@ def new_gridlines(self, grid_helper=None):
         gridlines = grid_helper.new_gridlines(self)
         return gridlines
 
-    def _init_gridlines(self, grid_helper=None):
-        # It is done inside the cla.
-        self.gridlines = self.new_gridlines(grid_helper)
-
     def clear(self):
         # docstring inherited
-        # gridlines need to be created before clear() since clear calls grid()
-        self._init_gridlines()
+
+        # Init gridlines before clear() as clear() calls grid().
+        self.gridlines = gridlines = GridlinesCollection(
+            None, transform=self.transData,
+            colors=rcParams['grid.color'],
+            linestyles=rcParams['grid.linestyle'],
+            linewidths=rcParams['grid.linewidth'])
+        self._set_artist_props(gridlines)
+        gridlines.set_grid_helper(self.get_grid_helper())
+
         super().clear()
 
-        # the clip_path should be set after Axes.clear() since that's
-        # when a patch is created.
-        self.gridlines.set_clip_path(self.axes.patch)
+        # clip_path is set after Axes.clear(): that's when a patch is created.
+        gridlines.set_clip_path(self.axes.patch)
 
-        self._init_axis_artists()
+        # Init axis artists.
+        self._axislines = mpl_axes.Axes.AxisDict(self)
+        new_fixed_axis = self.get_grid_helper().new_fixed_axis
+        self._axislines.update({
+            loc: new_fixed_axis(loc=loc, axes=self, axis_direction=loc)
+            for loc in ["bottom", "top", "left", "right"]})
+        for axisline in [self._axislines["top"], self._axislines["right"]]:
+            axisline.label.set_visible(False)
+            axisline.major_ticklabels.set_visible(False)
+            axisline.minor_ticklabels.set_visible(False)
 
     def get_grid_helper(self):
         return self._grid_helper
@@ -564,27 +563,18 @@ def new_floating_axis(self, nth_coord, value, axis_direction="bottom"):
 
 class AxesZero(Axes):
 
-    def _init_axis_artists(self):
-        super()._init_axis_artists()
-
-        new_floating_axis = self._grid_helper.new_floating_axis
-        xaxis_zero = new_floating_axis(nth_coord=0,
-                                       value=0.,
-                                       axis_direction="bottom",
-                                       axes=self)
-
-        xaxis_zero.line.set_clip_path(self.patch)
-        xaxis_zero.set_visible(False)
-        self._axislines["xzero"] = xaxis_zero
-
-        yaxis_zero = new_floating_axis(nth_coord=1,
-                                       value=0.,
-                                       axis_direction="left",
-                                       axes=self)
-
-        yaxis_zero.line.set_clip_path(self.patch)
-        yaxis_zero.set_visible(False)
-        self._axislines["yzero"] = yaxis_zero
+    def clear(self):
+        super().clear()
+        new_floating_axis = self.get_grid_helper().new_floating_axis
+        self._axislines.update(
+            xzero=new_floating_axis(
+                nth_coord=0, value=0., axis_direction="bottom", axes=self),
+            yzero=new_floating_axis(
+                nth_coord=1, value=0., axis_direction="left", axes=self),
+        )
+        for k in ["xzero", "yzero"]:
+            self._axislines[k].line.set_clip_path(self.patch)
+            self._axislines[k].set_visible(False)
 
 
 SubplotZero = maxes.subplot_class_factory(AxesZero)