Support standard formatters in axisartist.

Ideally, axisartist-specific formatters (and locators) should be
deprecated and removed in the future.

Author: anntzer

doc/users/next_whats_new/stdfmt-axisartist.rst

@@ -0,0 +1,3 @@
+``axisartist`` can now be used together with standard ``Formatters``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+... instead of being limited to axisartist-specific ones.

lib/mpl_toolkits/axisartist/floating_axes.py

@@ -222,10 +222,10 @@ def _update_grid(self, x1, y1, x2, y2):
         grid_info["lon_info"] = lon_levs, lon_n, lon_factor
         grid_info["lat_info"] = lat_levs, lat_n, lat_factor
 
-        grid_info["lon_labels"] = grid_finder.tick_formatter1(
-            "bottom", lon_factor, lon_levs)
-        grid_info["lat_labels"] = grid_finder.tick_formatter2(
-            "bottom", lat_factor, lat_levs)
+        grid_info["lon_labels"] = grid_finder._format_ticks(
+            1, "bottom", lon_factor, lon_levs)
+        grid_info["lat_labels"] = grid_finder._format_ticks(
+            2, "bottom", lat_factor, lat_levs)
 
         lon_values = lon_levs[:lon_n] / lon_factor
         lat_values = lat_levs[:lat_n] / lat_factor

lib/mpl_toolkits/axisartist/grid_finder.py

@@ -1,6 +1,6 @@
 import numpy as np
 
-from matplotlib import ticker as mticker
+from matplotlib import ticker as mticker, _api
 from matplotlib.transforms import Bbox, Transform
 
 
@@ -150,6 +150,19 @@ def __init__(self,
         self.tick_formatter2 = tick_formatter2
         self.set_transform(transform)
 
+    def _format_ticks(self, idx, direction, factor, levels):
+        """
+        Helper to support both standard formatters (inheriting from
+        `.mticker.Formatter`) and axisartist-specific ones; should be called instead of
+        directly calling ``self.tick_formatter1`` and ``self.tick_formatter2``.  This
+        method should be considered as a temporary workaround which will be removed in
+        the future at the same time as axisartist-specific formatters.
+        """
+        fmt = _api.check_getitem(
+            {1: self.tick_formatter1, 2: self.tick_formatter2}, idx=idx)
+        return (fmt.format_ticks(levels) if isinstance(fmt, mticker.Formatter)
+                else fmt(direction, factor, levels))
+
     def get_grid_info(self, x1, y1, x2, y2):
         """
         lon_values, lat_values : list of grid values. if integer is given,
@@ -192,14 +205,14 @@ def get_grid_info(self, x1, y1, x2, y2):
         tck_labels = grid_info["lon"]["tick_labels"] = {}
         for direction in ["left", "bottom", "right", "top"]:
             levs = grid_info["lon"]["tick_levels"][direction]
-            tck_labels[direction] = self.tick_formatter1(
-                direction, lon_factor, levs)
+            tck_labels[direction] = self._format_ticks(
+                1, direction, lon_factor, levs)
 
         tck_labels = grid_info["lat"]["tick_labels"] = {}
         for direction in ["left", "bottom", "right", "top"]:
             levs = grid_info["lat"]["tick_levels"][direction]
-            tck_labels[direction] = self.tick_formatter2(
-                direction, lat_factor, levs)
+            tck_labels[direction] = self._format_ticks(
+                2, direction, lat_factor, levs)
 
         return grid_info
 

lib/mpl_toolkits/axisartist/grid_helper_curvelinear.py

@@ -137,10 +137,10 @@ def update_lim(self, axes):
             "extremes": (lon_min, lon_max, lat_min, lat_max),
             "lon_info": (lon_levs, lon_n, np.asarray(lon_factor)),
             "lat_info": (lat_levs, lat_n, np.asarray(lat_factor)),
-            "lon_labels": grid_finder.tick_formatter1(
-                "bottom", lon_factor, lon_levs),
-            "lat_labels": grid_finder.tick_formatter2(
-                "bottom", lat_factor, lat_levs),
+            "lon_labels": grid_finder._format_ticks(
+                1, "bottom", lon_factor, lon_levs),
+            "lat_labels": grid_finder._format_ticks(
+                2, "bottom", lat_factor, lat_levs),
             "line_xy": (xx, yy),
         }
 

lib/mpl_toolkits/axisartist/tests/baseline_images/test_grid_helper_curvelinear/polar_box.png

@@ -3,6 +3,7 @@
 import matplotlib.pyplot as plt
 from matplotlib.path import Path
 from matplotlib.projections import PolarAxes
+from matplotlib.ticker import FuncFormatter
 from matplotlib.transforms import Affine2D, Transform
 from matplotlib.testing.decorators import image_comparison
 
@@ -75,11 +76,8 @@ def inverted(self):
     ax1.grid(True)
 
 
-# Remove tol & kerning_factor when this test image is regenerated.
-@image_comparison(['polar_box.png'], style='default', tol=0.27)
+@image_comparison(['polar_box.png'], style='default', tol=0.02)
 def test_polar_box():
-    plt.rcParams['text.kerning_factor'] = 6
-
     fig = plt.figure(figsize=(5, 5))
 
     # PolarAxes.PolarTransform takes radian. However, we want our coordinate
@@ -95,13 +93,13 @@ def test_polar_box():
                                                      lon_minmax=None,
                                                      lat_minmax=(0, np.inf))
 
-    grid_locator1 = angle_helper.LocatorDMS(12)
-    tick_formatter1 = angle_helper.FormatterDMS()
-
-    grid_helper = GridHelperCurveLinear(tr,
-                                        extreme_finder=extreme_finder,
-                                        grid_locator1=grid_locator1,
-                                        tick_formatter1=tick_formatter1)
+    grid_helper = GridHelperCurveLinear(
+        tr,
+        extreme_finder=extreme_finder,
+        grid_locator1=angle_helper.LocatorDMS(12),
+        tick_formatter1=angle_helper.FormatterDMS(),
+        tick_formatter2=FuncFormatter(lambda x, p: "eight" if x == 8 else f"{int(x)}"),
+    )
 
     ax1 = SubplotHost(fig, 1, 1, 1, grid_helper=grid_helper)