Add minor ticks on and off in Axis

Author: n-aswin

doc/api/axis_api.rst

@@ -112,6 +112,9 @@ Ticks, tick labels and Offset text
 
    Axis.axis_date
 
+   Axis.minorticks_off
+   Axis.minorticks_on
+
 
 Data and view intervals
 -----------------------

doc/users/next_whats_new/axis_minorticks_toggle.rst

@@ -0,0 +1,6 @@
+Toggle minorticks on Axis
+------------------------------
+
+Minor ticks on an `~matplotlib.axis.Axis` can be displayed or removed using
+`~matplotlib.axis.Axis.minorticks_on` and `~matplotlib.axis.Axis.minorticks_off`;
+e.g.: ``ax.xaxis.minorticks_on()``. See also `~matplotlib.axes.Axes.minorticks_on`.

lib/matplotlib/axes/_base.py

@@ -3987,22 +3987,13 @@ def minorticks_on(self):
         Displaying minor ticks may reduce performance; you may turn them off
         using `minorticks_off()` if drawing speed is a problem.
         """
-        for ax in (self.xaxis, self.yaxis):
-            scale = ax.get_scale()
-            if scale == 'log':
-                s = ax._scale
-                ax.set_minor_locator(mticker.LogLocator(s.base, s.subs))
-            elif scale == 'symlog':
-                s = ax._scale
-                ax.set_minor_locator(
-                    mticker.SymmetricalLogLocator(s._transform, s.subs))
-            else:
-                ax.set_minor_locator(mticker.AutoMinorLocator())
+        self.xaxis.minorticks_on()
+        self.yaxis.minorticks_on()
 
     def minorticks_off(self):
         """Remove minor ticks from the Axes."""
-        self.xaxis.set_minor_locator(mticker.NullLocator())
-        self.yaxis.set_minor_locator(mticker.NullLocator())
+        self.xaxis.minorticks_off()
+        self.yaxis.minorticks_off()
 
     # Interactive manipulation
 

lib/matplotlib/axis.py

@@ -928,6 +928,44 @@ def reset_ticks(self):
         except AttributeError:
             pass
 
+    def minorticks_on(self):
+        """
+        Display default minor ticks on the Axis, depending on the scale
+        (`~.axis.Axis.get_scale`).
+
+        Scales use specific minor locators:
+
+        - log: `~.LogLocator`
+        - symlog: `~.SymmetricalLogLocator`
+        - asinh: `~.AsinhLocator`
+        - logit: `~.LogitLocator`
+        - default: `~.AutoMinorLocator`
+
+        Displaying minor ticks may reduce performance; you may turn them off
+        using `minorticks_off()` if drawing speed is a problem.
+        """
+        scale = self.get_scale()
+        if scale == 'log':
+            s = self._scale
+            self.set_minor_locator(mticker.LogLocator(s.base, s.subs))
+        elif scale == 'symlog':
+            s = self._scale
+            self.set_minor_locator(
+                mticker.SymmetricalLogLocator(s._transform, s.subs))
+        elif scale == 'asinh':
+            s = self._scale
+            self.set_minor_locator(
+                    mticker.AsinhLocator(s.linear_width, base=s._base,
+                                         subs=s._subs))
+        elif scale == 'logit':
+            self.set_minor_locator(mticker.LogitLocator(minor=True))
+        else:
+            self.set_minor_locator(mticker.AutoMinorLocator())
+
+    def minorticks_off(self):
+        """Remove minor ticks from the Axis."""
+        self.set_minor_locator(mticker.NullLocator())
+
     def set_tick_params(self, which='major', reset=False, **kwargs):
         """
         Set appearance parameters for ticks, ticklabels, and gridlines.

lib/matplotlib/axis.pyi

@@ -151,6 +151,8 @@ class Axis(martist.Artist):
     units: Any
     def clear(self) -> None: ...
     def reset_ticks(self) -> None: ...
+    def minorticks_on(self) -> None: ...
+    def minorticks_off(self) -> None: ...
     def set_tick_params(
         self,
         which: Literal["major", "minor", "both"] = ...,

lib/matplotlib/tests/test_ticker.py

@@ -1734,6 +1734,46 @@ def minorticksubplot(xminor, yminor, i):
     minorticksubplot(True, True, 4)
 
 
+def test_minorticks_toggle():
+    """
+    Test toggling minor ticks
+
+    Test `.Axis.minorticks_on()` and `.Axis.minorticks_off()`. Testing is
+    limited to a subset of built-in scales - `'linear'`, `'log'`, `'asinh'`
+    and `'logit'`. `symlog` scale does not seem to have a working minor
+    locator and is omitted. In future, this test should cover all scales in
+    `matplotlib.scale.get_scale_names()`.
+    """
+    fig = plt.figure()
+    def minortickstoggle(xminor, yminor, scale, i):
+        ax = fig.add_subplot(2, 2, i)
+        ax.set_xscale(scale)
+        ax.set_yscale(scale)
+        if not xminor and not yminor:
+            ax.minorticks_off()
+        if xminor and not yminor:
+            ax.xaxis.minorticks_on()
+            ax.yaxis.minorticks_off()
+        if not xminor and yminor:
+            ax.xaxis.minorticks_off()
+            ax.yaxis.minorticks_on()
+        if xminor and yminor:
+            ax.minorticks_on()
+
+        assert (len(ax.xaxis.get_minor_ticks()) > 0) == xminor
+        assert (len(ax.yaxis.get_minor_ticks()) > 0) == yminor
+
+    scales = ['linear', 'log', 'asinh', 'logit']
+    for scale in scales:
+        minortickstoggle(False, False, scale, 1)
+        minortickstoggle(True, False, scale, 2)
+        minortickstoggle(False, True, scale, 3)
+        minortickstoggle(True, True, scale, 4)
+        fig.clear()
+
+    plt.close(fig)
+
+
 @pytest.mark.parametrize('remove_overlapping_locs, expected_num',
                          ((True, 6),
                           (None, 6),  # this tests the default