Cleanup custom_scale example.

anntzer · anntzer · commit 92abfba49ca2 · 2020-01-16T14:09:30.000+01:00
- Various docstring cleanups.
- The axisbelow hack is not necessary anymore.
- Use a normal FuncFormatter instead of a custom Formatter subclass.
  (We can reuse the same formatter for major and minor ticks.)
- No need to make political statements about the Mercator projection.
diff --git a/examples/scales/custom_scale.py b/examples/scales/custom_scale.py
@@ -7,28 +7,23 @@
 Mercator Projection.
 
 Unless you are making special use of the `~.Transform` class, you probably
-don't need to use this verbose method, and instead can use
-`~.matplotlib.scale.FuncScale` and the ``'function'`` option of
-`~.matplotlib.axes.Axes.set_xscale` and `~.matplotlib.axes.Axes.set_yscale`.
+don't need to use this verbose method, and instead can use `~.scale.FuncScale`
+and the ``'function'`` option of `~.Axes.set_xscale` and `~.Axes.set_yscale`.
 See the last example in :doc:`/gallery/scales/scales`.
 """
 
 import numpy as np
 from numpy import ma
 from matplotlib import scale as mscale
 from matplotlib import transforms as mtransforms
-from matplotlib.ticker import Formatter, FixedLocator
+from matplotlib.ticker import FixedLocator, FuncFormatter
 from matplotlib import rcParams
 
 
-# BUG: this example fails with any other setting of axisbelow
-rcParams['axes.axisbelow'] = False
-
-
 class MercatorLatitudeScale(mscale.ScaleBase):
     """
     Scales data in range -pi/2 to pi/2 (-90 to 90 degrees) using
-    the system used to scale latitudes in a Mercator projection.
+    the system used to scale latitudes in a Mercator__ projection.
 
     The scale function:
       ln(tan(y) + sec(y))
@@ -40,8 +35,7 @@ class MercatorLatitudeScale(mscale.ScaleBase):
     there is user-defined threshold, above and below which nothing
     will be plotted.  This defaults to +/- 85 degrees.
 
-    source:
-    http://en.wikipedia.org/wiki/Mercator_projection
+    __ http://en.wikipedia.org/wiki/Mercator_projection
     """
 
     # The scale class must have a member ``name`` that defines the string used
@@ -77,21 +71,16 @@ def set_default_locators_and_formatters(self, axis):
         scale.  This is only required if the scale requires custom
         locators and formatters.  Writing custom locators and
         formatters is rather outside the scope of this example, but
-        there are many helpful examples in ``ticker.py``.
+        there are many helpful examples in :mod:`.ticker`.
 
-        In our case, the Mercator example uses a fixed locator from
-        -90 to 90 degrees and a custom formatter class to put convert
-        the radians to degrees and put a degree symbol after the
-        value::
+        In our case, the Mercator example uses a fixed locator from -90 to 90
+        degrees and a custom formatter to convert the radians to degrees and
+        put a degree symbol after the value.
         """
-        class DegreeFormatter(Formatter):
-            def __call__(self, x, pos=None):
-                return "%d\N{DEGREE SIGN}" % np.degrees(x)
-
-        axis.set_major_locator(FixedLocator(
-            np.radians(np.arange(-90, 90, 10))))
-        axis.set_major_formatter(DegreeFormatter())
-        axis.set_minor_formatter(DegreeFormatter())
+        fmt = FuncFormatter(
+            lambda x, pos=None: f"{np.degrees(x):.0f}\N{DEGREE SIGN}")
+        axis.set(major_locator=FixedLocator(np.radians(range(-90, 90, 10))),
+                 major_formatter=fmt, minor_formatter=fmt)
 
     def limit_range_for_scale(self, vmin, vmax, minpos):
         """
@@ -176,7 +165,7 @@ def inverted(self):
 
     plt.xlabel('Longitude')
     plt.ylabel('Latitude')
-    plt.title('Mercator: Projection of the Oppressor')
+    plt.title('Mercator projection')
     plt.grid(True)
 
     plt.show()
