matplotlib · QuLogic · Feb 6, 2017 · Jan 27, 2017
diff --git a/examples/pylab_examples/histogram_percent_demo.py b/examples/pylab_examples/histogram_percent_demo.py
@@ -1,30 +1,19 @@
 import matplotlib
 from numpy.random import randn
 import matplotlib.pyplot as plt
-from matplotlib.ticker import FuncFormatter
+from matplotlib.ticker import PercentFormatter
 
 
-def to_percent(y, position):
-    # Ignore the passed in position. This has the effect of scaling the default
-    # tick locations.
-    s = str(100 * y)
-
-    # The percent symbol needs escaping in latex
-    if matplotlib.rcParams['text.usetex'] is True:
-        return s + r'$\%$'
-    else:
-        return s + '%'
-
 x = randn(5000)
 
-# Make a normed histogram. It'll be multiplied by 100 later.
-plt.hist(x, bins=50, normed=True)
+# Create a figure with some axes. This makes it easier to set the
+# formatter later, since that is only available through the OO API.
+fig, ax = plt.subplots()
 
-# Create the formatter using the function to_percent. This multiplies all the
-# default labels by 100, making them all percentages
-formatter = FuncFormatter(to_percent)
+# Make a normed histogram. It'll be multiplied by 100 later.
+ax.hist(x, bins=50, normed=True)
 
-# Set the formatter
-plt.gca().yaxis.set_major_formatter(formatter)
+# Set the formatter. `xmax` sets the value that maps to 100%.
+ax.yaxis.set_major_formatter(PercentFormatter(xmax=1))
 
 plt.show()
diff --git a/examples/ticks_and_spines/tick-formatters.py b/examples/ticks_and_spines/tick-formatters.py
@@ -21,8 +21,8 @@ def setup(ax):
     ax.patch.set_alpha(0.0)
 
 
-plt.figure(figsize=(8, 5))
-n = 6
+plt.figure(figsize=(8, 6))
+n = 7
 
 # Null formatter
 ax = plt.subplot(n, 1, 1)
@@ -87,6 +87,15 @@ def major_formatter(x, pos):
 ax.text(0.0, 0.1, "StrMethodFormatter('{x}')",
         fontsize=15, transform=ax.transAxes)
 
+# Percent formatter
+ax = plt.subplot(n, 1, 7)
+setup(ax)
+ax.xaxis.set_major_locator(ticker.MultipleLocator(1.00))
+ax.xaxis.set_minor_locator(ticker.MultipleLocator(0.25))
+ax.xaxis.set_major_formatter(ticker.PercentFormatter(xmax=5))
+ax.text(0.0, 0.1, "PercentFormatter(xmax=5)",
+        fontsize=15, transform=ax.transAxes)
+
 # Push the top of the top axes outside the figure because we only show the
 # bottom spine.
 plt.subplots_adjust(left=0.05, right=0.95, bottom=0.05, top=1.05)

diff --git a/lib/matplotlib/tests/test_ticker.py b/lib/matplotlib/tests/test_ticker.py
@@ -510,13 +510,40 @@ def test_basic(self):
         tmp_form = mticker.FormatStrFormatter('%05d')
         assert '00002' == tmp_form(2)
 
-        # test str.format() style formatter
-        tmp_form = mticker.StrMethodFormatter('{x:05d}')
-        assert '00002' == tmp_form(2)
 
-        # test str.format() style formatter with `pos`
-        tmp_form = mticker.StrMethodFormatter('{x:03d}-{pos:02d}')
-        assert '002-01' == tmp_form(2, 1)
+class TestStrMethodFormatter(object):
+    test_data = [
+        ('{x:05d}', (2,), '00002'),
+        ('{x:03d}-{pos:02d}', (2, 1), '002-01'),
+    ]
+
+    @pytest.mark.parametrize('format, input, expected', test_data)
+    def test_basic(self, format, input, expected):
+        fmt = mticker.StrMethodFormatter(format)
+        assert fmt(*input) == expected
+
+
+class TestEngFormatter(object):
+    format_data = [
+        ('', 0.1, u'100 m'),
+        ('', 1, u'1'),
+        ('', 999.9, u'999.9'),
+        ('', 1001, u'1.001 k'),
+        (u's', 0.1, u'100 ms'),
+        (u's', 1, u'1 s'),
+        (u's', 999.9, u'999.9 s'),
+        (u's', 1001, u'1.001 ks'),
+    ]
+
+    @pytest.mark.parametrize('unit, input, expected', format_data)
+    def test_formatting(self, unit, input, expected):
+        """
+        Test the formatting of EngFormatter with some inputs, against
+        instances with and without units. Cases focus on when no SI
+        prefix is present, for values in [1, 1000).
+        """
+        fmt = mticker.EngFormatter(unit)
+        assert fmt(input) == expected
 
 
 class TestPercentFormatter(object):
@@ -525,12 +552,12 @@ class TestPercentFormatter(object):
         (100, 0, '%', 120, 100, '120%'),
         (100, 0, '%', 100, 90, '100%'),
         (100, 0, '%', 90, 50, '90%'),
-        (100, 0, '%', 1.7, 40, '2%'),
+        (100, 0, '%', -1.7, 40, '-2%'),
         (100, 1, '%', 90.0, 100, '90.0%'),
         (100, 1, '%', 80.1, 90, '80.1%'),
         (100, 1, '%', 70.23, 50, '70.2%'),
         # 60.554 instead of 60.55: see https://bugs.python.org/issue5118
-        (100, 1, '%', 60.554, 40, '60.6%'),
+        (100, 1, '%', -60.554, 40, '-60.6%'),
         # Check auto decimals over different intervals and values
         (100, None, '%', 95, 1, '95.00%'),
         (1.0, None, '%', 3, 6, '300%'),
@@ -565,33 +592,24 @@ class TestPercentFormatter(object):
         'Custom percent symbol',
     ]
 
+    latex_data = [
+        (False, False, r'50\{t}%'),
+        (False, True, r'50\\\{t\}\%'),
+        (True, False, r'50\{t}%'),
+        (True, True, r'50\{t}%'),
+    ]
+
     @pytest.mark.parametrize(
             'xmax, decimals, symbol, x, display_range, expected',
             percent_data, ids=percent_ids)
-    def test_percentformatter(self, xmax, decimals, symbol,
-                              x, display_range, expected):
+    def test_basic(self, xmax, decimals, symbol,
+                   x, display_range, expected):
         formatter = mticker.PercentFormatter(xmax, decimals, symbol)
-        assert formatter.format_pct(x, display_range) == expected
-
-
-class TestEngFormatter(object):
-    format_data = [
-        ('', 0.1, u'100 m'),
-        ('', 1, u'1'),
-        ('', 999.9, u'999.9'),
-        ('', 1001, u'1.001 k'),
-        (u's', 0.1, u'100 ms'),
-        (u's', 1, u'1 s'),
-        (u's', 999.9, u'999.9 s'),
-        (u's', 1001, u'1.001 ks'),
-    ]
-
-    @pytest.mark.parametrize('unit, input, expected', format_data)
-    def test_formatting(self, unit, input, expected):
-        """
-        Test the formatting of EngFormatter with some inputs, against
-        instances with and without units. Cases focus on when no SI
-        prefix is present, for values in [1, 1000).
-        """
-        fmt = mticker.EngFormatter(unit)
-        assert fmt(input) == expected
+        with matplotlib.rc_context(rc={'text.usetex': False}):
+            assert formatter.format_pct(x, display_range) == expected
+
+    @pytest.mark.parametrize('is_latex, usetex, expected', latex_data)
+    def test_latex(self, is_latex, usetex, expected):
+        fmt = mticker.PercentFormatter(symbol='\\{t}%', is_latex=is_latex)
+        with matplotlib.rc_context(rc={'text.usetex': usetex}):
+            assert fmt.format_pct(50, 100) == expected
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -1285,16 +1285,19 @@ class PercentFormatter(Formatter):
     situation is where `xmax` is 1.0.
 
     `symbol` is a string which will be appended to the label. It may be
-    `None` or empty to indicate that no symbol should be used.
+    `None` or empty to indicate that no symbol should be used. LaTeX
+    special characters are escaped in `symbol` whenever latex mode is
+    enabled, unless `is_latex` is `True`.
 
     `decimals` is the number of decimal places to place after the point.
     If it is set to `None` (the default), the number will be computed
     automatically.
     """
-    def __init__(self, xmax=100, decimals=None, symbol='%'):
+    def __init__(self, xmax=100, decimals=None, symbol='%', is_latex=False):
         self.xmax = xmax + 0.0
         self.decimals = decimals
-        self.symbol = symbol
+        self._symbol = symbol
+        self._is_latex = is_latex
 
     def __call__(self, x, pos=None):
         """
@@ -1350,13 +1353,35 @@ def format_pct(self, x, display_range):
             decimals = self.decimals
         s = '{x:0.{decimals}f}'.format(x=x, decimals=int(decimals))
 
-        if self.symbol:
-            return s + self.symbol
-        return s
+        return s + self.symbol
 
     def convert_to_pct(self, x):
         return 100.0 * (x / self.xmax)
 
+    @property
+    def symbol(self):
+        """
+        The configured percent symbol as a string.
+
+        If LaTeX is enabled via ``rcParams['text.usetex']``, the special
+        characters `{'#', '$', '%', '&', '~', '_', '^', '\\', '{', '}'}`
+        are automatically escaped in the string.
+        """
+        symbol = self._symbol
+        if not symbol:
+            symbol = ''
+        elif rcParams['text.usetex'] and not self._is_latex:
+            # Source: http://www.personal.ceu.hu/tex/specchar.htm
+            # Backslash must be first for this to work correctly since
+            # it keeps getting added in
+            for spec in r'\#$%&~_^{}':
+                symbol = symbol.replace(spec, '\\' + spec)
+        return symbol
+
+    @symbol.setter
+    def symbol(self):
+        self._symbol = symbol
+
 
 class Locator(TickHelper):
     """