Merge pull request matplotlib#26981 from Vashesh08/Latex

Fixes Issue matplotlib#26377 - Auto-escape % Symbol in Latex in pie labels

Author: QuLogic

doc/users/next_whats_new/pie_percent_latex.rst

@@ -0,0 +1,11 @@
+Percent sign in pie labels auto-escaped with ``usetex=True``
+------------------------------------------------------------
+
+It is common, with `.Axes.pie`, to specify labels that include a percent sign
+(``%``), which denotes a comment for LaTeX. When enabling LaTeX with
+:rc:`text.usetex` or passing ``textprops={"usetex": True}``, this would cause
+the percent sign to disappear.
+
+Now, the percent sign is automatically escaped (by adding a preceding
+backslash) so that it appears regardless of the ``usetex`` setting. If you have
+pre-escaped the percent sign, this will be detected, and remain as is.

lib/matplotlib/axes/_axes.py

@@ -4,6 +4,7 @@
 import math
 from numbers import Integral, Number, Real
 
+import re
 import numpy as np
 from numpy import ma
 
@@ -3377,6 +3378,9 @@ def get_next_color():
                 else:
                     raise TypeError(
                         'autopct must be callable or a format string')
+                if mpl._val_or_rc(textprops.get("usetex"), "text.usetex"):
+                    # escape % (i.e. \%) if it is not already escaped
+                    s = re.sub(r"([^\\])%", r"\1\\%", s)
                 t = self.text(xt, yt, s,
                               clip_on=False,
                               horizontalalignment='center',

lib/matplotlib/tests/test_axes.py

@@ -38,6 +38,7 @@
     assert_allclose, assert_array_equal, assert_array_almost_equal)
 from matplotlib.testing.decorators import (
     image_comparison, check_figures_equal, remove_ticks_and_titles)
+from matplotlib.testing._markers import needs_usetex
 
 # Note: Some test cases are run twice: once normally and once with labeled data
 #       These two must be defined in the same test function or need to have
@@ -9008,3 +9009,16 @@ def test_boxplot_tick_labels():
     # Test the new tick_labels parameter
     axs[1].boxplot(data, tick_labels=['A', 'B', 'C'])
     assert [l.get_text() for l in axs[1].get_xticklabels()] == ['A', 'B', 'C']
+
+
+@needs_usetex
+@check_figures_equal()
+def test_latex_pie_percent(fig_test, fig_ref):
+
+    data = [20, 10, 70]
+
+    ax = fig_test.subplots()
+    ax.pie(data, autopct="%1.0f%%", textprops={'usetex': True})
+
+    ax1 = fig_ref.subplots()
+    ax1.pie(data, autopct=r"%1.0f\%%", textprops={'usetex': True})