matplotlib · jklymak · Jan 15, 2019 · Jan 4, 2019 · anntzer · Jan 4, 2019
diff --git a/.flake8 b/.flake8
@@ -54,7 +54,6 @@ per-file-ignores =
     mpl_toolkits/axes_grid1/axes_size.py: E272, E501
     mpl_toolkits/axes_grid1/colorbar.py: E225, E501
     mpl_toolkits/axes_grid1/inset_locator.py: E501
-    mpl_toolkits/axes_grid1/mpl_axes.py: E501
     mpl_toolkits/axisartist/angle_helper.py: E221
     mpl_toolkits/axisartist/clip_path.py: E225, E501
     mpl_toolkits/axisartist/floating_axes.py: E225, E402, E501

diff --git a/examples/units/basic_units.py b/examples/units/basic_units.py
@@ -122,9 +122,8 @@ def __new__(cls, value, unit):
         # generate a new subclass for value
         value_class = type(value)
         try:
-            subcls = type('TaggedValue_of_%s' % (value_class.__name__),
-                          tuple([cls, value_class]),
-                          {})
+            subcls = type(f'TaggedValue_of_{value_class.__name__}',
+                          (cls, value_class), {})
             if subcls not in units.registry:
                 units.registry[subcls] = basicConverter
             return object.__new__(subcls)
@@ -196,7 +195,7 @@ def __init__(self, name, fullname=None):
         self.conversions = dict()
 
     def __repr__(self):
-        return 'BasicUnit(%s)' % self.name
+        return f'BasicUnit({self.name})'
 
     def __str__(self):
         return self.fullname
@@ -314,9 +313,9 @@ def rad_fn(x, pos=None):
     elif n == -2:
         return r'$-\pi$'
     elif n % 2 == 0:
-        return r'$%s\pi$' % (n//2,)
+        return fr'${n//2}\pi$'
     else:
-        return r'$%s\pi/2$' % (n,)
+        return fr'${n}\pi/2$'
 
 
 class BasicUnitConverter(units.ConversionInterface):

diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -844,8 +844,8 @@ def __setitem__(self, key, val):
             dict.__setitem__(self, key, cval)
         except KeyError:
             raise KeyError(
-                '%s is not a valid rc parameter. See rcParams.keys() for a '
-                'list of valid parameters.' % (key,))
+                f"{key} is not a valid rc parameter (see rcParams.keys() for "
+                f"a list of valid parameters)")
 
     def __getitem__(self, key):
         if key in _deprecated_map:

diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -2291,8 +2291,7 @@ def margins(self, *margins, x=None, y=None, tight=True):
 
         if x is None and y is None:
             if tight is not True:
-                cbook._warn_external(
-                    'ignoring tight=%r in get mode' % (tight,))
+                cbook._warn_external(f'ignoring tight={tight!r} in get mode')
             return self._xmargin, self._ymargin
 
         if x is not None:

diff --git a/lib/matplotlib/axes/_subplots.py b/lib/matplotlib/axes/_subplots.py
@@ -55,13 +55,12 @@ def __init__(self, fig, *args, **kwargs):
             else:
                 if num < 1 or num > rows*cols:
                     raise ValueError(
-                        ("num must be 1 <= num <= {maxn}, not {num}"
-                        ).format(maxn=rows*cols, num=num))
+                        f"num must be 1 <= num <= {rows*cols}, not {num}")
                 self._subplotspec = GridSpec(
                         rows, cols, figure=self.figure)[int(num) - 1]
                 # num - 1 for converting from MATLAB to python indexing
         else:
-            raise ValueError('Illegal argument(s) to subplot: %s' % (args,))
+            raise ValueError(f'Illegal argument(s) to subplot: {args}')
 
         self.update_params()
 

diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
@@ -879,7 +879,7 @@ def recurse(obj, start, all, current_path):
                 recurse(referent, start, all, current_path + [obj])
 
     for obj in objects:
-        outstream.write("Examining: %r\n" % (obj,))
+        outstream.write(f"Examining: {obj!r}\n")
         recurse(obj, obj, {}, [])
 
 

diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -638,10 +638,8 @@ def _set_label(self):
         self.stale = True
 
     def set_label(self, label, **kw):
-        '''
-        Label the long axis of the colorbar
-        '''
-        self._label = '%s' % (label, )
+        """Label the long axis of the colorbar."""
+        self._label = str(label)
         self._labelkw = kw
         self._set_label()
 

diff --git a/lib/matplotlib/container.py b/lib/matplotlib/container.py
@@ -52,10 +52,11 @@ def set_label(self, s):
 
         Parameters
         ----------
-        s : string or anything printable with '%s' conversion.
+        s : object
+            Any object other than None gets converted to its `str`.
         """
         if s is not None:
-            self._label = '%s' % (s, )
+            self._label = str(s)
         else:
             self._label = None
         self.pchanged()

diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -1951,9 +1951,9 @@ def __setstate__(self, state):
         restore_to_pylab = state.pop('_restore_to_pylab', False)
 
         if version != _mpl_version:
-            cbook._warn_external("This figure was saved with matplotlib "
-                                 "version %s and is unlikely to function "
-                                 "correctly." % (version,))
+            cbook._warn_external(
+                f"This figure was saved with matplotlib version {version} and "
+                f"is unlikely to function correctly.")
 
         self.__dict__ = state
 

diff --git a/lib/matplotlib/lines.py b/lib/matplotlib/lines.py
@@ -180,30 +180,26 @@ def _slice_or_none(in_v, slc):
             inds = inds.argmin(axis=1)
             inds = np.unique(inds)
             # return, we are done here
-            return Path(verts[inds],
-                        _slice_or_none(codes, inds))
+            return Path(verts[inds], _slice_or_none(codes, inds))
         else:
             raise ValueError(
-                '`markevery` is a tuple with len 2, but its second element is '
-                'not an int or a float; markevery=%s' % (markevery,))
+                f"markevery={markevery!r} is a tuple with len 2, but its "
+                f"second element is not an int or a float")
 
     elif isinstance(markevery, slice):
         # mazol tov, it's already a slice, just return
         return Path(verts[markevery], _slice_or_none(codes, markevery))
 
     elif np.iterable(markevery):
-        #fancy indexing
+        # fancy indexing
         try:
             return Path(verts[markevery], _slice_or_none(codes, markevery))
-
         except (ValueError, IndexError):
-            raise ValueError('`markevery` is iterable but '
-                'not a valid form of numpy fancy indexing; '
-                'markevery=%s' % (markevery,))
+            raise ValueError(
+                f"markevery={markevery!r} is iterable but not a valid numpy "
+                f"fancy index")
     else:
-        raise ValueError('Value of `markevery` is not '
-            'recognized; '
-            'markevery=%s' % (markevery,))
+        raise ValueError(f"markevery={markevery!r} is not a recognized value")
 
 
 @cbook._define_aliases({
@@ -264,17 +260,16 @@ class Line2D(Artist):
 
     def __str__(self):
         if self._label != "":
-            return "Line2D(%s)" % (self._label)
+            return f"Line2D({self._label})"
         elif self._x is None:
             return "Line2D()"
         elif len(self._x) > 3:
-            return "Line2D((%g,%g),(%g,%g),...,(%g,%g))"\
-                % (self._x[0], self._y[0], self._x[0],
-                   self._y[0], self._x[-1], self._y[-1])
+            return "Line2D((%g,%g),(%g,%g),...,(%g,%g))" % (
+                self._x[0], self._y[0], self._x[0],
+                self._y[0], self._x[-1], self._y[-1])
         else:
-            return "Line2D(%s)"\
-                % (",".join(["(%g,%g)" % (x, y) for x, y
-                             in zip(self._x, self._y)]))
+            return "Line2D(%s)" % ",".join(
+                map("({:g},{:g})".format, self._x, self._y))
 
     def __init__(self, xdata, ydata,
                  linewidth=None,  # all Nones default to rc

diff --git a/lib/matplotlib/testing/jpl_units/UnitDblConverter.py b/lib/matplotlib/testing/jpl_units/UnitDblConverter.py
@@ -21,9 +21,9 @@ def rad_fn(x, pos=None):
     elif n == 2:
         return r'$\pi$'
     elif n % 2 == 0:
-        return r'$%s\pi$' % (n/2,)
+        return fr'${n//2}\pi$'
     else:
-        return r'$%s\pi/2$' % (n,)
+        return fr'${n}\pi/2$'
 
 
 class UnitDblConverter(units.ConversionInterface):

diff --git a/lib/matplotlib/tests/test_rcparams.py b/lib/matplotlib/tests/test_rcparams.py
@@ -163,8 +163,8 @@ def test_Bug_2543():
 @pytest.mark.parametrize('color_type, param_dict, target', legend_color_tests,
                          ids=legend_color_test_ids)
 def test_legend_colors(color_type, param_dict, target):
-    param_dict['legend.%scolor' % (color_type, )] = param_dict.pop('color')
-    get_func = 'get_%scolor' % (color_type, )
+    param_dict[f'legend.{color_type}color'] = param_dict.pop('color')
+    get_func = f'get_{color_type}color'
 
     with mpl.rc_context(param_dict):
         _, ax = plt.subplots()

diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
@@ -1145,12 +1145,14 @@ def set_text(self, s):
 
         Parameters
         ----------
-        s : string or object castable to string (but ``None`` becomes ``''``)
+        s : object
+            Any object gets converted to its `str`, except ``None`` which
+            becomes ``''``.
         """
         if s is None:
             s = ''
         if s != self._text:
-            self._text = '%s' % (s,)
+            self._text = str(s)
             self.stale = True
 
     @staticmethod

diff --git a/lib/mpl_toolkits/axes_grid1/axes_divider.py b/lib/mpl_toolkits/axes_grid1/axes_divider.py
@@ -396,7 +396,7 @@ def __init__(self, fig, *args, horizontal=None, vertical=None,
                 self._subplotspec = GridSpec(rows, cols)[int(num)-1]
                 # num - 1 for converting from MATLAB to python indexing
         else:
-            raise ValueError('Illegal argument(s) to subplot: %s' % (args,))
+            raise ValueError(f'Illegal argument(s) to subplot: {args}')
 
         # total = rows*cols
         # num -= 1    # convert from matlab to python indexing

diff --git a/lib/mpl_toolkits/axes_grid1/mpl_axes.py b/lib/mpl_toolkits/axes_grid1/mpl_axes.py
@@ -70,7 +70,8 @@ def __init__(self, axis, axisnum, spine):
         elif isinstance(axis, YAxis):
             self._axis_direction = ["left", "right"][axisnum-1]
         else:
-            raise ValueError("axis must be instance of XAxis or YAxis : %s is provided" % (axis,))
+            raise ValueError(
+                f"axis must be instance of XAxis or YAxis, but got {axis}")
         Artist.__init__(self)
 
     @property

diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -435,8 +435,7 @@ def margins(self, *margins, x=None, y=None, z=None, tight=True):
 
         if x is None and y is None and z is None:
             if tight is not True:
-                cbook._warn_external(
-                    'ignoring tight=%r in get mode' % (tight,))
+                cbook._warn_external(f'ignoring tight={tight!r} in get mode')
             return self._xmargin, self._ymargin, self._zmargin
 
         if x is not None:

diff --git a/lib/mpl_toolkits/tests/test_axisartist_angle_helper.py b/lib/mpl_toolkits/tests/test_axisartist_angle_helper.py
@@ -118,12 +118,11 @@ def test_formatters(Formatter, regex, direction, factor, values):
     prev_degree = prev_minute = prev_second = None
     for tick, value in zip(result, values):
         m = regex.match(tick)
-        assert m is not None, '"%s" is not an expected tick format.' % (tick, )
+        assert m is not None, f'{tick!r} is not an expected tick format.'
 
         sign = sum(m.group(sign + '_sign') is not None
                    for sign in ('degree', 'minute', 'second'))
-        assert sign <= 1, \
-            'Only one element of tick "%s" may have a sign.' % (tick, )
+        assert sign <= 1, f'Only one element of tick {tick!r} may have a sign.'
         sign = 1 if sign == 0 else -1
 
         degree = float(m.group('degree') or prev_degree or 0)
@@ -135,7 +134,7 @@ def test_formatters(Formatter, regex, direction, factor, values):
         else:
             expected_value = pytest.approx(value / factor)
         assert sign * dms2float(degree, minute, second) == expected_value, \
-            '"%s" does not match expected tick value.' % (tick, )
+            f'{tick!r} does not match expected tick value.'
 
         prev_degree = degree
         prev_minute = minute