From c0f839bf9b332c410f393ed330271fbcf8128f40 Mon Sep 17 00:00:00 2001
From: Antony Lee <anntzer.lee@gmail.com>
Date: Sun, 23 Sep 2018 16:05:10 +0200
Subject: [PATCH] Add helper function to check that an argument is in a list of
 strings.

---
 doc/api/next_api_changes/2019-01-22-AL.rst    |  5 ++
 lib/matplotlib/axes/_base.py                  | 10 ++--
 lib/matplotlib/axes/_subplots.py              |  2 +-
 lib/matplotlib/axis.py                        | 11 ++--
 lib/matplotlib/backends/backend_ps.py         |  9 ++--
 .../backends/backend_webagg_core.py           |  6 +--
 lib/matplotlib/cbook/__init__.py              | 22 ++++++++
 lib/matplotlib/collections.py                 | 11 ++--
 lib/matplotlib/contour.py                     |  4 +-
 lib/matplotlib/figure.py                      | 28 ++++------
 lib/matplotlib/font_manager.py                |  6 +--
 lib/matplotlib/lines.py                       | 28 +++-------
 lib/matplotlib/mathtext.py                    | 12 ++---
 lib/matplotlib/projections/geo.py             | 10 ++--
 lib/matplotlib/projections/polar.py           | 14 +++--
 lib/matplotlib/quiver.py                      |  5 +-
 lib/matplotlib/scale.py                       |  8 ++-
 lib/matplotlib/text.py                        | 21 +++-----
 lib/matplotlib/tri/tripcolor.py               |  5 +-
 lib/matplotlib/widgets.py                     | 12 ++---
 lib/mpl_toolkits/axes_grid1/axes_divider.py   | 11 ++--
 lib/mpl_toolkits/axes_grid1/axes_size.py      |  6 +--
 lib/mpl_toolkits/axes_grid1/parasite_axes.py  | 10 ++--
 lib/mpl_toolkits/axisartist/axis_artist.py    | 53 +++++--------------
 lib/mpl_toolkits/mplot3d/axes3d.py            |  3 +-
 25 files changed, 121 insertions(+), 191 deletions(-)
 create mode 100644 doc/api/next_api_changes/2019-01-22-AL.rst

diff --git a/doc/api/next_api_changes/2019-01-22-AL.rst b/doc/api/next_api_changes/2019-01-22-AL.rst
new file mode 100644
index 000000000000..5ba6747a087c
--- /dev/null
+++ b/doc/api/next_api_changes/2019-01-22-AL.rst
@@ -0,0 +1,5 @@
+Changed exceptions
+``````````````````
+
+- `mpl_toolkits.axes_grid1.axes_size.GetExtentHelper` now raises `ValueError`
+  for invalid directions instead of `KeyError`.
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
index 5fde8bf01539..c2b48b9d9e1b 100644
--- a/lib/matplotlib/axes/_base.py
+++ b/lib/matplotlib/axes/_base.py
@@ -1328,8 +1328,7 @@ def set_adjustable(self, adjustable, share=False):
         which the adjustments for aspect ratios are done sequentially
         and independently on each Axes as it is drawn.
         """
-        if adjustable not in ('box', 'datalim'):
-            raise ValueError("argument must be 'box', or 'datalim'")
+        cbook._check_in_list(["box", "datalim"], adjustable=adjustable)
         if share:
             axes = set(self._shared_x_axes.get_siblings(self)
                        + self._shared_y_axes.get_siblings(self))
@@ -2745,9 +2744,7 @@ def grid(self, b=None, which='major', axis='both', **kwargs):
         """
         if len(kwargs):
             b = True
-        if axis not in ['x', 'y', 'both']:
-            raise ValueError("The argument 'axis' must be one of 'x', 'y' or "
-                             "'both'.")
+        cbook._check_in_list(['x', 'y', 'both'], axis=axis)
         if axis in ['x', 'both']:
             self.xaxis.grid(b, which=which, **kwargs)
         if axis in ['y', 'both']:
@@ -2963,8 +2960,7 @@ def tick_params(self, axis='both', **kwargs):
         also be red.  Gridlines will be red and translucent.
 
         """
-        if axis not in ['x', 'y', 'both']:
-            raise ValueError("axis must be one of 'x', 'y' or 'both'")
+        cbook._check_in_list(['x', 'y', 'both'], axis=axis)
         if axis in ['x', 'both']:
             xkw = dict(kwargs)
             xkw.pop('left', None)
diff --git a/lib/matplotlib/axes/_subplots.py b/lib/matplotlib/axes/_subplots.py
index 5becb1aae371..001f5f1624cb 100644
--- a/lib/matplotlib/axes/_subplots.py
+++ b/lib/matplotlib/axes/_subplots.py
@@ -1,7 +1,7 @@
 import functools
 import uuid
 
-from matplotlib import docstring
+from matplotlib import cbook, docstring
 import matplotlib.artist as martist
 from matplotlib.axes._axes import Axes
 from matplotlib.gridspec import GridSpec, SubplotSpec
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
index cc5e2d6bd187..fd3ee314dad0 100644
--- a/lib/matplotlib/axis.py
+++ b/lib/matplotlib/axis.py
@@ -204,9 +204,7 @@ def _set_labelrotation(self, labelrotation):
         else:
             mode = 'default'
             angle = labelrotation
-        if mode not in ('auto', 'default'):
-            raise ValueError("Label rotation mode must be 'default' or "
-                             "'auto', not '{}'.".format(mode))
+        cbook._check_in_list(['auto', 'default'], labelrotation=mode)
         self._labelrotation = (mode, angle)
 
     def apply_tickdir(self, tickdir):
@@ -1269,8 +1267,7 @@ def get_ticklabels(self, minor=False, which=None):
             elif which == 'both':
                 return self.get_majorticklabels() + self.get_minorticklabels()
             else:
-                raise ValueError("`which` must be one of ('minor', 'major', "
-                                 "'both') not " + str(which))
+                cbook._check_in_list(['major', 'minor', 'both'], which=which)
         if minor:
             return self.get_minorticklabels()
         return self.get_majorticklabels()
@@ -1426,9 +1423,7 @@ def grid(self, b=None, which='major', **kwargs):
                                      'grid will be enabled.')
             b = True
         which = which.lower()
-        if which not in ['major', 'minor', 'both']:
-            raise ValueError("The argument 'which' must be one of 'major', "
-                             "'minor' or 'both'.")
+        cbook._check_in_list(['major', 'minor', 'both'], which=which)
         gridkw = {'grid_' + item[0]: item[1] for item in kwargs.items()}
 
         if which in ['minor', 'both']:
diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
index 2b4f3233c0e4..529bed5f41c1 100644
--- a/lib/matplotlib/backends/backend_ps.py
+++ b/lib/matplotlib/backends/backend_ps.py
@@ -838,12 +838,9 @@ def _print_ps(self, outfile, format, *args,
                                (papertype, ', '.join(papersize)))
 
         orientation = orientation.lower()
-        if orientation == 'landscape':
-            isLandscape = True
-        elif orientation == 'portrait':
-            isLandscape = False
-        else:
-            raise RuntimeError('Orientation must be "portrait" or "landscape"')
+        cbook._check_in_list(['landscape', 'portrait'],
+                             orientation=orientation)
+        isLandscape = (orientation == 'landscape')
 
         self.figure.set_dpi(72)  # Override the dpi kwarg
 
diff --git a/lib/matplotlib/backends/backend_webagg_core.py b/lib/matplotlib/backends/backend_webagg_core.py
index 16ca41d7fdd4..72bd66f9e066 100644
--- a/lib/matplotlib/backends/backend_webagg_core.py
+++ b/lib/matplotlib/backends/backend_webagg_core.py
@@ -20,9 +20,9 @@
 import numpy as np
 import tornado
 
+from matplotlib import backend_bases, cbook, _png
 from matplotlib.backends import backend_agg
 from matplotlib.backend_bases import _Backend
-from matplotlib import backend_bases, _png
 
 _log = logging.getLogger(__name__)
 
@@ -163,10 +163,8 @@ def set_image_mode(self, mode):
         Note: diff images may not contain transparency, therefore upon
         draw this mode may be changed if the resulting image has any
         transparent component.
-
         """
-        if mode not in ['full', 'diff']:
-            raise ValueError('image mode must be either full or diff.')
+        cbook._check_in_list(['full', 'diff'], mode=mode)
         if self._current_image_mode != mode:
             self._current_image_mode = mode
             self.handle_send_image_mode(None)
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
index 24ae18d1a143..e935ceed2bad 100644
--- a/lib/matplotlib/cbook/__init__.py
+++ b/lib/matplotlib/cbook/__init__.py
@@ -2111,6 +2111,12 @@ def _unmultiplied_rgba8888_to_premultiplied_argb32(rgba8888):
 
 
 def _check_and_log_subprocess(command, logger, **kwargs):
+    """
+    Run *command* using `subprocess.check_output`.  If it succeeds, return the
+    output (stdout and stderr); if not, raise an exception whose text includes
+    the failed command and captured output.  Both the command and the output
+    are logged at DEBUG level on *logger*.
+    """
     logger.debug(command)
     try:
         report = subprocess.check_output(
@@ -2134,3 +2140,19 @@ def _check_not_matrix(**kwargs):
     for k, v in kwargs.items():
         if isinstance(v, np.matrix):
             raise TypeError(f"Argument {k!r} cannot be a np.matrix")
+
+
+def _check_in_list(values, **kwargs):
+    """
+    For each *key, value* pair in *kwargs*, check that *value* is in *values*;
+    if not, raise an appropriate ValueError.
+
+    Examples
+    --------
+    >>> cbook._check_in_list(["foo", "bar"], arg=arg, other_arg=other_arg)
+    """
+    for k, v in kwargs.items():
+        if v not in values:
+            raise ValueError(
+                "{!r} is not a valid value for {}; supported values are {}"
+                .format(v, k, ', '.join(map(repr, values))))
diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
index af6f8ed12a98..3a460efd878b 100644
--- a/lib/matplotlib/collections.py
+++ b/lib/matplotlib/collections.py
@@ -464,8 +464,8 @@ def set_offset_position(self, offset_position):
         ----------
         offset_position : {'screen', 'data'}
         """
-        if offset_position not in ('screen', 'data'):
-            raise ValueError("offset_position must be 'screen' or 'data'")
+        cbook._check_in_list(['screen', 'data'],
+                             offset_position=offset_position)
         self._offset_position = offset_position
         self.stale = True
 
@@ -1490,7 +1490,8 @@ def __init__(self,
                         coord1 in positions]
             self._is_horizontal = False
         else:
-            raise ValueError("orientation must be 'horizontal' or 'vertical'")
+            cbook._check_in_list(['horizontal', 'vertical'],
+                                 orientation=orientation)
 
         LineCollection.__init__(self,
                                 segments,
@@ -1583,8 +1584,8 @@ def set_orientation(self, orientation=None):
         elif orientation.lower() == 'vertical':
             is_horizontal = False
         else:
-            raise ValueError("orientation must be 'horizontal' or 'vertical'")
-
+            cbook._check_in_list(['horizontal', 'vertical'],
+                                 orientation=orientation)
         if is_horizontal == self.is_horizontal():
             return
         self.switch_orientation()
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
index 22bd15749cbf..f874d2e63d45 100644
--- a/lib/matplotlib/contour.py
+++ b/lib/matplotlib/contour.py
@@ -842,9 +842,7 @@ def __init__(self, ax, *args,
         else:
             self.logscale = False
 
-        if self.origin not in [None, 'lower', 'upper', 'image']:
-            raise ValueError("If given, *origin* must be one of [ 'lower' |"
-                             " 'upper' | 'image']")
+        cbook._check_in_list([None, 'lower', 'upper', 'image'], origin=origin)
         if self.extent is not None and len(self.extent) != 4:
             raise ValueError("If given, *extent* must be '[ *None* |"
                              " (x0,x1,y0,y1) ]'")
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
index 0872f10247e8..a1ffa1a86e66 100644
--- a/lib/matplotlib/figure.py
+++ b/lib/matplotlib/figure.py
@@ -1524,23 +1524,17 @@ def subplots(self, nrows=1, ncols=1, sharex=False, sharey=False,
             sharex = "all" if sharex else "none"
         if isinstance(sharey, bool):
             sharey = "all" if sharey else "none"
-        share_values = ["all", "row", "col", "none"]
-        if sharex not in share_values:
-            # This check was added because it is very easy to type
-            # `subplots(1, 2, 1)` when `subplot(1, 2, 1)` was intended.
-            # In most cases, no error will ever occur, but mysterious behavior
-            # will result because what was intended to be the subplot index is
-            # instead treated as a bool for sharex.
-            if isinstance(sharex, Integral):
-                cbook._warn_external("sharex argument to subplots() was an "
-                                     "integer. Did you intend to use "
-                                     "subplot() (without 's')?")
-
-            raise ValueError("sharex [%s] must be one of %s" %
-                             (sharex, share_values))
-        if sharey not in share_values:
-            raise ValueError("sharey [%s] must be one of %s" %
-                             (sharey, share_values))
+        # This check was added because it is very easy to type
+        # `subplots(1, 2, 1)` when `subplot(1, 2, 1)` was intended.
+        # In most cases, no error will ever occur, but mysterious behavior
+        # will result because what was intended to be the subplot index is
+        # instead treated as a bool for sharex.
+        if isinstance(sharex, Integral):
+            cbook._warn_external(
+                "sharex argument to subplots() was an integer.  Did you "
+                "intend to use subplot() (without 's')?")
+        cbook._check_in_list(["all", "row", "col", "none"],
+                             sharex=sharex, sharey=sharey)
         if subplot_kw is None:
             subplot_kw = {}
         if gridspec_kw is None:
diff --git a/lib/matplotlib/font_manager.py b/lib/matplotlib/font_manager.py
index 5e3ea26b278f..a1a687fa5934 100644
--- a/lib/matplotlib/font_manager.py
+++ b/lib/matplotlib/font_manager.py
@@ -759,8 +759,7 @@ def set_style(self, style):
         """
         if style is None:
             style = rcParams['font.style']
-        if style not in ('normal', 'italic', 'oblique'):
-            raise ValueError("style must be normal, italic or oblique")
+        cbook._check_in_list(['normal', 'italic', 'oblique'], style=style)
         self._slant = style
     set_slant = set_style
 
@@ -770,8 +769,7 @@ def set_variant(self, variant):
         """
         if variant is None:
             variant = rcParams['font.variant']
-        if variant not in ('normal', 'small-caps'):
-            raise ValueError("variant must be normal or small-caps")
+        cbook._check_in_list(['normal', 'small-caps'], variant=variant)
         self._variant = variant
 
     def set_weight(self, weight):
diff --git a/lib/matplotlib/lines.py b/lib/matplotlib/lines.py
index 7288330c5ce9..aafb56ac2415 100644
--- a/lib/matplotlib/lines.py
+++ b/lib/matplotlib/lines.py
@@ -1083,8 +1083,7 @@ def set_drawstyle(self, drawstyle):
         """
         if drawstyle is None:
             drawstyle = 'default'
-        if drawstyle not in self.drawStyles:
-            raise ValueError('Unrecognized drawstyle {!r}'.format(drawstyle))
+        cbook._check_in_list(self.drawStyles, drawstyle=drawstyle)
         if self._drawstyle != drawstyle:
             self.stale = True
             # invalidate to trigger a recache of the path
@@ -1181,13 +1180,9 @@ def set_linestyle(self, ls):
             if ls in [' ', '', 'none']:
                 ls = 'None'
 
+            cbook._check_in_list([*self._lineStyles, *ls_mapper_r], ls=ls)
             if ls not in self._lineStyles:
-                try:
-                    ls = ls_mapper_r[ls]
-                except KeyError:
-                    raise ValueError("Invalid linestyle {!r}; see docs of "
-                                     "Line2D.set_linestyle for valid values"
-                                     .format(ls))
+                ls = ls_mapper_r[ls]
             self._linestyle = ls
         else:
             self._linestyle = '--'
@@ -1362,9 +1357,7 @@ def set_dash_joinstyle(self, s):
             For examples see :doc:`/gallery/lines_bars_and_markers/joinstyle`.
         """
         s = s.lower()
-        if s not in self.validJoin:
-            raise ValueError('set_dash_joinstyle passed "%s";\n' % (s,)
-                             + 'valid joinstyles are %s' % (self.validJoin,))
+        cbook._check_in_list(self.validJoin, s=s)
         if self._dashjoinstyle != s:
             self.stale = True
         self._dashjoinstyle = s
@@ -1379,10 +1372,7 @@ def set_solid_joinstyle(self, s):
             For examples see :doc:`/gallery/lines_bars_and_markers/joinstyle`.
         """
         s = s.lower()
-        if s not in self.validJoin:
-            raise ValueError('set_solid_joinstyle passed "%s";\n' % (s,)
-                             + 'valid joinstyles are %s' % (self.validJoin,))
-
+        cbook._check_in_list(self.validJoin, s=s)
         if self._solidjoinstyle != s:
             self.stale = True
         self._solidjoinstyle = s
@@ -1412,9 +1402,7 @@ def set_dash_capstyle(self, s):
         s : {'butt', 'round', 'projecting'}
         """
         s = s.lower()
-        if s not in self.validCap:
-            raise ValueError('set_dash_capstyle passed "%s";\n' % (s,)
-                             + 'valid capstyles are %s' % (self.validCap,))
+        cbook._check_in_list(self.validCap, s=s)
         if self._dashcapstyle != s:
             self.stale = True
         self._dashcapstyle = s
@@ -1428,9 +1416,7 @@ def set_solid_capstyle(self, s):
         s : {'butt', 'round', 'projecting'}
         """
         s = s.lower()
-        if s not in self.validCap:
-            raise ValueError('set_solid_capstyle passed "%s";\n' % (s,)
-                             + 'valid capstyles are %s' % (self.validCap,))
+        cbook._check_in_list(self.validCap, s=s)
         if self._solidcapstyle != s:
             self.stale = True
         self._solidcapstyle = s
diff --git a/lib/matplotlib/mathtext.py b/lib/matplotlib/mathtext.py
index 6d83d9d8a330..62a2107e0f93 100644
--- a/lib/matplotlib/mathtext.py
+++ b/lib/matplotlib/mathtext.py
@@ -3351,14 +3351,10 @@ def parse(self, s, dpi = 72, prop = None):
             font_output = StandardPsFonts(prop)
         else:
             backend = self._backend_mapping[self._output]()
-            fontset = rcParams['mathtext.fontset']
-            fontset_class = self._font_type_mapping.get(fontset.lower())
-            if fontset_class is not None:
-                font_output = fontset_class(prop, backend)
-            else:
-                raise ValueError(
-                    "mathtext.fontset must be either 'cm', 'dejavuserif', "
-                    "'dejavusans', 'stix', 'stixsans', or 'custom'")
+            fontset = rcParams['mathtext.fontset'].lower()
+            cbook._check_in_list(self._font_type_mapping, fontset=fontset)
+            fontset_class = self._font_type_mapping[fontset]
+            font_output = fontset_class(prop, backend)
 
         fontsize = prop.get_size_in_points()
 
diff --git a/lib/matplotlib/projections/geo.py b/lib/matplotlib/projections/geo.py
index cc4e24376bba..7d1a96c91d21 100644
--- a/lib/matplotlib/projections/geo.py
+++ b/lib/matplotlib/projections/geo.py
@@ -1,6 +1,6 @@
 import numpy as np
 
-from matplotlib import rcParams
+from matplotlib import cbook, rcParams
 from matplotlib.axes import Axes
 import matplotlib.axis as maxis
 from matplotlib.patches import Circle
@@ -118,9 +118,7 @@ def _get_affine_transform(self):
             .translate(0.5, 0.5)
 
     def get_xaxis_transform(self, which='grid'):
-        if which not in ['tick1', 'tick2', 'grid']:
-            raise ValueError(
-                "'which' must be one of 'tick1', 'tick2', or 'grid'")
+        cbook._check_in_list(['tick1', 'tick2', 'grid'], which=which)
         return self._xaxis_transform
 
     def get_xaxis_text1_transform(self, pad):
@@ -130,9 +128,7 @@ def get_xaxis_text2_transform(self, pad):
         return self._xaxis_text2_transform, 'top', 'center'
 
     def get_yaxis_transform(self, which='grid'):
-        if which not in ['tick1', 'tick2', 'grid']:
-            raise ValueError(
-                "'which' must be one of 'tick1', 'tick2', or 'grid'")
+        cbook._check_in_list(['tick1', 'tick2', 'grid'], which=which)
         return self._yaxis_transform
 
     def get_yaxis_text1_transform(self, pad):
diff --git a/lib/matplotlib/projections/polar.py b/lib/matplotlib/projections/polar.py
index 59f2bc83a4a6..e32ed5b79d72 100644
--- a/lib/matplotlib/projections/polar.py
+++ b/lib/matplotlib/projections/polar.py
@@ -3,12 +3,12 @@
 
 import numpy as np
 
+from matplotlib import cbook, rcParams
 from matplotlib.axes import Axes
 import matplotlib.axis as maxis
 import matplotlib.markers as mmarkers
 import matplotlib.patches as mpatches
 import matplotlib.path as mpath
-from matplotlib import rcParams
 import matplotlib.ticker as mticker
 import matplotlib.transforms as mtransforms
 import matplotlib.spines as mspines
@@ -908,9 +908,7 @@ def _set_lim_and_transforms(self):
             self._r_label_position + self.transData)
 
     def get_xaxis_transform(self, which='grid'):
-        if which not in ['tick1', 'tick2', 'grid']:
-            raise ValueError(
-                "'which' must be one of 'tick1', 'tick2', or 'grid'")
+        cbook._check_in_list(['tick1', 'tick2', 'grid'], which=which)
         return self._xaxis_transform
 
     def get_xaxis_text1_transform(self, pad):
@@ -925,8 +923,7 @@ def get_yaxis_transform(self, which='grid'):
         elif which == 'grid':
             return self._yaxis_transform
         else:
-            raise ValueError(
-                "'which' must be one of 'tick1', 'tick2', or 'grid'")
+            cbook._check_in_list(['tick1', 'tick2', 'grid'], which=which)
 
     def get_yaxis_text1_transform(self, pad):
         thetamin, thetamax = self._realViewLim.intervalx
@@ -1085,8 +1082,9 @@ def set_theta_direction(self, direction):
         elif direction in ('counterclockwise', 'anticlockwise', 1):
             mtx[0, 0] = 1
         else:
-            raise ValueError(
-                "direction must be 1, -1, clockwise or counterclockwise")
+            cbook._check_in_list(
+                [-1, 1, 'clockwise', 'counterclockwise', 'anticlockwise'],
+                direction=direction)
         self._direction.invalidate()
 
     def get_theta_direction(self):
diff --git a/lib/matplotlib/quiver.py b/lib/matplotlib/quiver.py
index 512daaa5b4c1..fb1b784a8d68 100644
--- a/lib/matplotlib/quiver.py
+++ b/lib/matplotlib/quiver.py
@@ -459,10 +459,7 @@ def __init__(self, ax, *args,
         if pivot.lower() == 'mid':
             pivot = 'middle'
         self.pivot = pivot.lower()
-        if self.pivot not in self._PIVOT_VALS:
-            raise ValueError(
-                'pivot must be one of {keys}, you passed {inp}'.format(
-                      keys=self._PIVOT_VALS, inp=pivot))
+        cbook._check_in_list(self._PIVOT_VALS, pivot=self.pivot)
 
         self.transform = kw.pop('transform', ax.transData)
         kw.setdefault('facecolors', color)
diff --git a/lib/matplotlib/scale.py b/lib/matplotlib/scale.py
index 8ce9b68a7165..93bb610fb4ef 100644
--- a/lib/matplotlib/scale.py
+++ b/lib/matplotlib/scale.py
@@ -349,10 +349,12 @@ def __init__(self, axis, **kwargs):
             base = kwargs.pop('basex', 10.0)
             subs = kwargs.pop('subsx', None)
             nonpos = kwargs.pop('nonposx', 'clip')
+            cbook._check_in_list(['mask', 'clip'], nonposx=nonpos)
         else:
             base = kwargs.pop('basey', 10.0)
             subs = kwargs.pop('subsy', None)
             nonpos = kwargs.pop('nonposy', 'clip')
+            cbook._check_in_list(['mask', 'clip'], nonposy=nonpos)
 
         if len(kwargs):
             raise ValueError(("provided too many kwargs, can only pass "
@@ -360,8 +362,6 @@ def __init__(self, axis, **kwargs):
                               "{'basey', 'subsy', nonposy'}.  You passed ") +
                              "{!r}".format(kwargs))
 
-        if nonpos not in ['mask', 'clip']:
-            raise ValueError("nonposx, nonposy kwarg must be 'mask' or 'clip'")
         if base <= 0 or base == 1:
             raise ValueError('The log base cannot be <= 0 or == 1')
 
@@ -664,9 +664,7 @@ def __init__(self, axis, nonpos='mask'):
           values beyond ]0, 1[ can be masked as invalid, or clipped to a number
           very close to 0 or 1
         """
-        if nonpos not in ['mask', 'clip']:
-            raise ValueError("nonposx, nonposy kwarg must be 'mask' or 'clip'")
-
+        cbook._check_in_list(['mask', 'clip'], nonpos=nonpos)
         self._transform = LogitTransform(nonpos)
 
     def get_transform(self):
diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
index afc845f4ee2a..650689cdb629 100644
--- a/lib/matplotlib/text.py
+++ b/lib/matplotlib/text.py
@@ -939,10 +939,7 @@ def set_horizontalalignment(self, align):
         ----------
         align : {'center', 'right', 'left'}
         """
-        legal = ('center', 'right', 'left')
-        if align not in legal:
-            raise ValueError('Horizontal alignment must be one of %s' %
-                             str(legal))
+        cbook._check_in_list(['center', 'right', 'left'], align=align)
         self._horizontalalignment = align
         self.stale = True
 
@@ -957,10 +954,7 @@ def set_multialignment(self, align):
         ----------
         align : {'left', 'right', 'center'}
         """
-        legal = ('center', 'right', 'left')
-        if align not in legal:
-            raise ValueError('Horizontal alignment must be one of %s' %
-                             str(legal))
+        cbook._check_in_list(['center', 'right', 'left'], align=align)
         self._multialignment = align
         self.stale = True
 
@@ -1128,11 +1122,9 @@ def set_verticalalignment(self, align):
         ----------
         align : {'center', 'top', 'bottom', 'baseline', 'center_baseline'}
         """
-        legal = ('top', 'bottom', 'center', 'baseline', 'center_baseline')
-        if align not in legal:
-            raise ValueError('Vertical alignment must be one of %s' %
-                             str(legal))
-
+        cbook._check_in_list(
+            ['top', 'bottom', 'center', 'baseline', 'center_baseline'],
+            align=align)
         self._verticalalignment = align
         self.stale = True
 
@@ -1690,8 +1682,7 @@ def set_unit(self, unit):
         ----------
         unit : {'points', 'pixels'}
         '''
-        if unit not in ["points", "pixels"]:
-            raise ValueError("'unit' must be one of [ 'points' | 'pixels' ]")
+        cbook._check_in_list(["points", "pixels"], unit=unit)
         self._unit = unit
 
     def get_unit(self):
diff --git a/lib/matplotlib/tri/tripcolor.py b/lib/matplotlib/tri/tripcolor.py
index 71f5d2de6dc9..52dd3e9e2ba9 100644
--- a/lib/matplotlib/tri/tripcolor.py
+++ b/lib/matplotlib/tri/tripcolor.py
@@ -1,5 +1,6 @@
 import numpy as np
 
+from matplotlib import cbook
 from matplotlib.collections import PolyCollection, TriMesh
 from matplotlib.colors import Normalize
 from matplotlib.tri.triangulation import Triangulation
@@ -46,9 +47,7 @@ def tripcolor(ax, *args, alpha=1.0, norm=None, cmap=None, vmin=None,
     The remaining kwargs are the same as for
     :meth:`~matplotlib.axes.Axes.pcolor`.
     """
-    if shading not in ['flat', 'gouraud']:
-        raise ValueError("shading must be one of ['flat', 'gouraud'] "
-                         "not {0}".format(shading))
+    cbook._check_in_list(['flat', 'gouraud'], shading=shading)
 
     tri, args, kwargs = Triangulation.get_from_args_and_kwargs(*args, **kwargs)
 
diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
index 009998a53680..c4b6b82010b8 100644
--- a/lib/matplotlib/widgets.py
+++ b/lib/matplotlib/widgets.py
@@ -14,7 +14,7 @@
 
 import numpy as np
 
-from . import rcParams
+from . import cbook, rcParams
 from .lines import Line2D
 from .patches import Circle, Rectangle, Ellipse
 from .transforms import blended_transform_factory
@@ -1760,8 +1760,7 @@ def __init__(self, ax, onselect, direction, minspan=None, useblit=False,
 
         rectprops['animated'] = self.useblit
 
-        if direction not in ['horizontal', 'vertical']:
-            raise ValueError("direction must be 'horizontal' or 'vertical'")
+        cbook._check_in_list(['horizontal', 'vertical'], direction=direction)
         self.direction = direction
 
         self.rect = None
@@ -2109,9 +2108,7 @@ def __init__(self, ax, onselect, drawtype='box',
         self.minspanx = minspanx
         self.minspany = minspany
 
-        if spancoords not in ('data', 'pixels'):
-            raise ValueError("'spancoords' must be 'data' or 'pixels'")
-
+        cbook._check_in_list(['data', 'pixels'], spancoords=spancoords)
         self.spancoords = spancoords
         self.drawtype = drawtype
 
@@ -2193,7 +2190,8 @@ def _release(self, event):
             xmin, ymin = self.eventpress.x, self.eventpress.y
             xmax, ymax = self.eventrelease.x, self.eventrelease.y
         else:
-            raise ValueError('spancoords must be "data" or "pixels"')
+            cbook._check_in_list(['data', 'pixels'],
+                                 spancoords=self.spancoords)
 
         if xmin > xmax:
             xmin, xmax = xmax, xmin
diff --git a/lib/mpl_toolkits/axes_grid1/axes_divider.py b/lib/mpl_toolkits/axes_grid1/axes_divider.py
index 40fb5af9b231..cfaf9235d6bd 100644
--- a/lib/mpl_toolkits/axes_grid1/axes_divider.py
+++ b/lib/mpl_toolkits/axes_grid1/axes_divider.py
@@ -267,7 +267,6 @@ def new_locator(self, nx, ny, nx1=None, ny1=None):
         return AxesLocator(self, nx, ny, nx1, ny1)
 
     def append_size(self, position, size):
-
         if position == "left":
             self._horizontal.insert(0, size)
             self._xrefindex += 1
@@ -279,8 +278,8 @@ def append_size(self, position, size):
         elif position == "top":
             self._vertical.append(size)
         else:
-            raise ValueError("the position must be one of left," +
-                             " right, bottom, or top")
+            cbook._check_in_list(["left", "right", "bottom", "top"],
+                                 position=position)
 
     def add_auto_adjustable_area(self,
                                  use_axes, pad=0.1,
@@ -613,7 +612,6 @@ def append_axes(self, position, size, pad=None, add_to_figure=True,
 
          *size* and *pad* should be axes_grid.axes_size compatible.
         """
-
         if position == "left":
             ax = self.new_horizontal(size, pad, pack_start=True, **kwargs)
         elif position == "right":
@@ -623,9 +621,8 @@ def append_axes(self, position, size, pad=None, add_to_figure=True,
         elif position == "top":
             ax = self.new_vertical(size, pad, pack_start=False, **kwargs)
         else:
-            raise ValueError("the position must be one of left," +
-                             " right, bottom, or top")
-
+            cbook._check_in_list(["left", "right", "bottom", "top"],
+                                 position=position)
         if add_to_figure:
             self._fig.add_axes(ax)
         return ax
diff --git a/lib/mpl_toolkits/axes_grid1/axes_size.py b/lib/mpl_toolkits/axes_grid1/axes_size.py
index 91aa4123f04f..4edc50d323fc 100644
--- a/lib/mpl_toolkits/axes_grid1/axes_size.py
+++ b/lib/mpl_toolkits/axes_grid1/axes_size.py
@@ -1,5 +1,5 @@
 """
-Provides a classes of simple units that will be used with AxesDivider
+Provides classes of simple units that will be used with AxesDivider
 class (or others) to determine the size of each axes. The unit
 classes define `get_size` method that returns a tuple of two floats,
 meaning relative and absolute sizes, respectively.
@@ -11,6 +11,7 @@ class (or others) to determine the size of each axes. The unit
 
 from numbers import Number
 
+from matplotlib import cbook
 from matplotlib.axes import Axes
 
 
@@ -303,8 +304,7 @@ class GetExtentHelper(object):
     }
 
     def __init__(self, ax, direction):
-        if direction not in self._get_func_map:
-            raise KeyError("direction must be one of left, right, bottom, top")
+        cbook._check_in_list(self._get_func_map, direction=direction)
         self._ax_list = [ax] if isinstance(ax, Axes) else ax
         self._direction = direction
 
diff --git a/lib/mpl_toolkits/axes_grid1/parasite_axes.py b/lib/mpl_toolkits/axes_grid1/parasite_axes.py
index ccdd4b8a4034..de9e68856065 100644
--- a/lib/mpl_toolkits/axes_grid1/parasite_axes.py
+++ b/lib/mpl_toolkits/axes_grid1/parasite_axes.py
@@ -1,6 +1,6 @@
 import functools
 
-from matplotlib import artist as martist, transforms as mtransforms
+from matplotlib import artist as martist, cbook, transforms as mtransforms
 from matplotlib.axes import subplot_class_factory
 from matplotlib.transforms import Bbox
 from .mpl_axes import Axes
@@ -82,10 +82,8 @@ def _set_lim_and_transforms(self):
                 self.transAxes, self.transData)
 
     def set_viewlim_mode(self, mode):
-        if mode not in [None, "equal", "transform"]:
-            raise ValueError("Unknown mode: %s" % (mode,))
-        else:
-            self._viewlim_mode = mode
+        cbook._check_in_list([None, "equal", "transform"], mode=mode)
+        self._viewlim_mode = mode
 
     def get_viewlim_mode(self):
         return self._viewlim_mode
@@ -101,7 +99,7 @@ def update_viewlim(self):
             self.axes.viewLim.set(
                 viewlim.transformed(self.transAux.inverted()))
         else:
-            raise ValueError("Unknown mode: %s" % (self._viewlim_mode,))
+            cbook._check_in_list([None, "equal", "transform"], mode=mode)
 
     def _pcolor(self, super_pcolor, *XYC, **kwargs):
         if len(XYC) == 1:
diff --git a/lib/mpl_toolkits/axisartist/axis_artist.py b/lib/mpl_toolkits/axisartist/axis_artist.py
index 219e4306a3ec..585a700b5ccc 100644
--- a/lib/mpl_toolkits/axisartist/axis_artist.py
+++ b/lib/mpl_toolkits/axisartist/axis_artist.py
@@ -463,9 +463,7 @@ def get_text(self):
                                top=("bottom", "center"))
 
     def set_default_alignment(self, d):
-        if d not in ["left", "right", "top", "bottom"]:
-            raise ValueError(
-                'direction must be on of "left", "right", "top", "bottom"')
+        cbook._check_in_list(["left", "right", "top", "bottom"], d=d)
         va, ha = self._default_alignments[d]
         self.set_va(va)
         self.set_ha(ha)
@@ -476,9 +474,7 @@ def set_default_alignment(self, d):
                            top=180)
 
     def set_default_angle(self, d):
-        if d not in ["left", "right", "top", "bottom"]:
-            raise ValueError(
-                'direction must be on of "left", "right", "top", "bottom"')
+        cbook._check_in_list(["left", "right", "top", "bottom"], d=d)
         self.set_rotation(self._default_angles[d])
 
     def set_axis_direction(self, d):
@@ -500,9 +496,7 @@ def set_axis_direction(self, d):
         axis.
 
         """
-        if d not in ["left", "right", "top", "bottom"]:
-            raise ValueError(
-                'direction must be on of "left", "right", "top", "bottom"')
+        cbook._check_in_list(["left", "right", "top", "bottom"], d=d)
         self.set_default_alignment(d)
         self.set_default_angle(d)
 
@@ -558,8 +552,7 @@ def set_axis_direction(self, label_direction):
         Adjust the text angle and text alignment of ticklabels
         according to the matplotlib convention.
 
-        The *label_direction* must be one of [left, right, bottom,
-        top].
+        The *label_direction* must be one of [left, right, bottom, top].
 
         =====================    ========== ========= ========== ==========
         property                 left       bottom    right      top
@@ -569,15 +562,12 @@ def set_axis_direction(self, label_direction):
         ticklabel ha             right      center    right      center
         =====================    ========== ========= ========== ==========
 
-
         Note that the text angles are actually relative to (90 + angle
         of the direction to the ticklabel), which gives 0 for bottom
         axis.
         """
-
-        if label_direction not in ["left", "right", "top", "bottom"]:
-            raise ValueError(
-                'direction must be one of "left", "right", "top", "bottom"')
+        cbook._check_in_list(["left", "right", "top", "bottom"],
+                             label_direction=label_direction)
         self._axis_direction = label_direction
         self.set_default_alignment(label_direction)
         self.set_default_angle(label_direction)
@@ -831,8 +821,7 @@ def set_axis_direction(self, axis_direction):
         ticklabels, labels following the matplotlib convention for
         the rectangle axes.
 
-        The *axis_direction* must be one of [left, right, bottom,
-        top].
+        The *axis_direction* must be one of [left, right, bottom, top].
 
         =====================    ========== ========= ========== ==========
         property                 left       bottom    right      top
@@ -847,17 +836,13 @@ def set_axis_direction(self, axis_direction):
         axislabel ha             right      center    right      center
         =====================    ========== ========= ========== ==========
 
-
         Note that the direction "+" and "-" are relative to the direction of
         the increasing coordinate. Also, the text angles are actually
         relative to (90 + angle of the direction to the ticklabel),
         which gives 0 for bottom axis.
-
         """
-
-        if axis_direction not in ["left", "right", "top", "bottom"]:
-            raise ValueError(
-                'direction must be on of "left", "right", "top", "bottom"')
+        cbook._check_in_list(["left", "right", "top", "bottom"],
+                             axis_direction=axis_direction)
         self._axis_direction = axis_direction
         if axis_direction in ["left", "top"]:
             self.set_ticklabel_direction("-")
@@ -865,7 +850,6 @@ def set_axis_direction(self, axis_direction):
         else:
             self.set_ticklabel_direction("+")
             self.set_axislabel_direction("+")
-
         self.major_ticklabels.set_axis_direction(axis_direction)
         self.label.set_axis_direction(axis_direction)
 
@@ -880,14 +864,8 @@ def set_ticklabel_direction(self, tick_direction):
         ----------
         tick_direction : {"+", "-"}
         """
-
-        if tick_direction not in ["+", "-"]:
-            raise ValueError('direction must be one of "+", "-"')
-
-        if tick_direction == "-":
-            self._ticklabel_add_angle = 180
-        else:
-            self._ticklabel_add_angle = 0
+        cbook._check_in_list(["+", "-"], tick_direction=tick_direction)
+        self._ticklabel_add_angle = {"+": 0, "-": 180}[tick_direction]
 
     def invert_ticklabel_direction(self):
         self._ticklabel_add_angle = (self._ticklabel_add_angle + 180) % 360
@@ -905,13 +883,8 @@ def set_axislabel_direction(self, label_direction):
         ----------
         tick_direction : {"+", "-"}
         """
-        if label_direction not in ["+", "-"]:
-            raise ValueError('direction must be one of "+", "-"')
-
-        if label_direction == "-":
-            self._axislabel_add_angle = 180
-        else:
-            self._axislabel_add_angle = 0
+        cbook._check_in_list(["+", "-"], label_direction=label_direction)
+        self._axislabel_add_angle = {"+": 0, "-": 180}[label_direction]
 
     def get_transform(self):
         return self.axes.transAxes + self.offset_transform
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
index dd31670fd58e..f11e8de8e53e 100644
--- a/lib/mpl_toolkits/mplot3d/axes3d.py
+++ b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -1405,8 +1405,7 @@ def tick_params(self, axis='both', **kwargs):
         .. versionadded :: 1.1.0
             This function was added, but not tested. Please report any bugs.
         """
-        if axis not in ['x', 'y', 'z', 'both']:
-            raise ValueError("axis must be one of 'x', 'y', 'z' or 'both'")
+        cbook._check_in_list(['x', 'y', 'z', 'both'], axis=axis)
         if axis in ['x', 'y', 'both']:
             super().tick_params(axis, **kwargs)
         if axis in ['z', 'both']: