VRCycling/Assets/Plotting/venv/lib/python3.7/site-packages/matplotlib/__init__.py

"""
An object-oriented plotting library.

A procedural interface is provided by the companion pyplot module,
which may be imported directly, e.g.::

    import matplotlib.pyplot as plt

or using ipython::

    ipython

at your terminal, followed by::

    In [1]: %matplotlib
    In [2]: import matplotlib.pyplot as plt

at the ipython shell prompt.

For the most part, direct use of the object-oriented library is encouraged when
programming; pyplot is primarily for working interactively.  The exceptions are
the pyplot functions `.pyplot.figure`, `.pyplot.subplot`, `.pyplot.subplots`,
and `.pyplot.savefig`, which can greatly simplify scripting.

Modules include:

    :mod:`matplotlib.axes`
        The `~.axes.Axes` class.  Most pyplot functions are wrappers for
        `~.axes.Axes` methods.  The axes module is the highest level of OO
        access to the library.

    :mod:`matplotlib.figure`
        The `.Figure` class.

    :mod:`matplotlib.artist`
        The `.Artist` base class for all classes that draw things.

    :mod:`matplotlib.lines`
        The `.Line2D` class for drawing lines and markers.

    :mod:`matplotlib.patches`
        Classes for drawing polygons.

    :mod:`matplotlib.text`
        The `.Text` and `.Annotation` classes.

    :mod:`matplotlib.image`
        The `.AxesImage` and `.FigureImage` classes.

    :mod:`matplotlib.collections`
        Classes for efficient drawing of groups of lines or polygons.

    :mod:`matplotlib.colors`
        Color specifications and making colormaps.

    :mod:`matplotlib.cm`
        Colormaps, and the `.ScalarMappable` mixin class for providing color
        mapping functionality to other classes.

    :mod:`matplotlib.ticker`
        Calculation of tick mark locations and formatting of tick labels.

    :mod:`matplotlib.backends`
        A subpackage with modules for various GUI libraries and output formats.

The base matplotlib namespace includes:

    `~matplotlib.rcParams`
        Default configuration settings; their defaults may be overridden using
        a :file:`matplotlibrc` file.

    `~matplotlib.use`
        Setting the Matplotlib backend.  This should be called before any
        figure is created, because it is not possible to switch between
        different GUI backends after that.

Matplotlib was initially written by John D. Hunter (1968-2012) and is now
developed and maintained by a host of others.

Occasionally the internal documentation (python docstrings) will refer
to MATLAB®, a registered trademark of The MathWorks, Inc.
"""

import atexit
from collections import namedtuple
from collections.abc import MutableMapping
import contextlib
from distutils.version import LooseVersion
import functools
import importlib
import inspect
from inspect import Parameter
import locale
import logging
import os
from pathlib import Path
import pprint
import re
import shutil
import subprocess
import sys
import tempfile
import warnings

# cbook must import matplotlib only within function
# definitions, so it is safe to import from it here.
from . import cbook, rcsetup
from matplotlib.cbook import MatplotlibDeprecationWarning, sanitize_sequence
from matplotlib.cbook import mplDeprecation  # deprecated
from matplotlib.rcsetup import validate_backend, cycler

import numpy

# Get the version from the _version.py versioneer file. For a git checkout,
# this is computed based on the number of commits since the last tag.
from ._version import get_versions
__version__ = str(get_versions()['version'])
del get_versions

_log = logging.getLogger(__name__)

__bibtex__ = r"""@Article{Hunter:2007,
  Author    = {Hunter, J. D.},
  Title     = {Matplotlib: A 2D graphics environment},
  Journal   = {Computing in Science \& Engineering},
  Volume    = {9},
  Number    = {3},
  Pages     = {90--95},
  abstract  = {Matplotlib is a 2D graphics package used for Python
  for application development, interactive scripting, and
  publication-quality image generation across user
  interfaces and operating systems.},
  publisher = {IEEE COMPUTER SOC},
  year      = 2007
}"""


@cbook.deprecated("3.2")
def compare_versions(a, b):
    """Return whether version *a* is greater than or equal to version *b*."""
    if isinstance(a, bytes):
        cbook.warn_deprecated(
            "3.0", message="compare_versions arguments should be strs.")
        a = a.decode('ascii')
    if isinstance(b, bytes):
        cbook.warn_deprecated(
            "3.0", message="compare_versions arguments should be strs.")
        b = b.decode('ascii')
    if a:
        return LooseVersion(a) >= LooseVersion(b)
    else:
        return False


def _check_versions():

    # Quickfix to ensure Microsoft Visual C++ redistributable
    # DLLs are loaded before importing kiwisolver
    from . import ft2font

    for modname, minver in [
            ("cycler", "0.10"),
            ("dateutil", "2.1"),
            ("kiwisolver", "1.0.1"),
            ("numpy", "1.15"),
            ("pyparsing", "2.0.1"),
    ]:
        module = importlib.import_module(modname)
        if LooseVersion(module.__version__) < minver:
            raise ImportError("Matplotlib requires {}>={}; you have {}"
                              .format(modname, minver, module.__version__))


_check_versions()


# The decorator ensures this always returns the same handler (and it is only
# attached once).
@functools.lru_cache()
def _ensure_handler():
    """
    The first time this function is called, attach a `StreamHandler` using the
    same format as `logging.basicConfig` to the Matplotlib root logger.

    Return this handler every time this function is called.
    """
    handler = logging.StreamHandler()
    handler.setFormatter(logging.Formatter(logging.BASIC_FORMAT))
    _log.addHandler(handler)
    return handler


def set_loglevel(level):
    """
    Set Matplotlib's root logger and root logger handler level, creating
    the handler if it does not exist yet.

    Typically, one should call ``set_loglevel("info")`` or
    ``set_loglevel("debug")`` to get additional debugging information.

    Parameters
    ----------
    level : {"notset", "debug", "info", "warning", "error", "critical"}
        The log level of the handler.

    Notes
    -----
    The first time this function is called, an additional handler is attached
    to Matplotlib's root handler; this handler is reused every time and this
    function simply manipulates the logger and handler's level.
    """
    _log.setLevel(level.upper())
    _ensure_handler().setLevel(level.upper())


def _logged_cached(fmt, func=None):
    """
    Decorator that logs a function's return value, and memoizes that value.

    After ::

        @_logged_cached(fmt)
        def func(): ...

    the first call to *func* will log its return value at the DEBUG level using
    %-format string *fmt*, and memoize it; later calls to *func* will directly
    return that value.
    """
    if func is None:  # Return the actual decorator.
        return functools.partial(_logged_cached, fmt)

    called = False
    ret = None

    @functools.wraps(func)
    def wrapper(**kwargs):
        nonlocal called, ret
        if not called:
            ret = func(**kwargs)
            called = True
            _log.debug(fmt, ret)
        return ret

    return wrapper


_ExecInfo = namedtuple("_ExecInfo", "executable version")


class ExecutableNotFoundError(FileNotFoundError):
    """
    Error raised when an executable that Matplotlib optionally
    depends on can't be found.
    """
    pass


@functools.lru_cache()
def _get_executable_info(name):
    """
    Get the version of some executable that Matplotlib optionally depends on.

    .. warning:
       The list of executables that this function supports is set according to
       Matplotlib's internal needs, and may change without notice.

    Parameters
    ----------
    name : str
        The executable to query.  The following values are currently supported:
        "dvipng", "gs", "inkscape", "magick", "pdftops".  This list is subject
        to change without notice.

    Returns
    -------
    If the executable is found, a namedtuple with fields ``executable`` (`str`)
    and ``version`` (`distutils.version.LooseVersion`, or ``None`` if the
    version cannot be determined).

    Raises
    ------
    ExecutableNotFoundError
        If the executable is not found or older than the oldest version
        supported by Matplotlib.
    ValueError
        If the executable is not one that we know how to query.
    """

    def impl(args, regex, min_ver=None, ignore_exit_code=False):
        # Execute the subprocess specified by args; capture stdout and stderr.
        # Search for a regex match in the output; if the match succeeds, the
        # first group of the match is the version.
        # Return an _ExecInfo if the executable exists, and has a version of
        # at least min_ver (if set); else, raise ExecutableNotFoundError.
        try:
            output = subprocess.check_output(
                args, stderr=subprocess.STDOUT,
                universal_newlines=True, errors="replace")
        except subprocess.CalledProcessError as _cpe:
            if ignore_exit_code:
                output = _cpe.output
            else:
                raise ExecutableNotFoundError(str(_cpe)) from _cpe
        except OSError as _ose:
            raise ExecutableNotFoundError(str(_ose)) from _ose
        match = re.search(regex, output)
        if match:
            version = LooseVersion(match.group(1))
            if min_ver is not None and version < min_ver:
                raise ExecutableNotFoundError(
                    f"You have {args[0]} version {version} but the minimum "
                    f"version supported by Matplotlib is {min_ver}")
            return _ExecInfo(args[0], version)
        else:
            raise ExecutableNotFoundError(
                f"Failed to determine the version of {args[0]} from "
                f"{' '.join(args)}, which output {output}")

    if name == "dvipng":
        return impl(["dvipng", "-version"], "(?m)^dvipng(?: .*)? (.+)", "1.6")
    elif name == "gs":
        execs = (["gswin32c", "gswin64c", "mgs", "gs"]  # "mgs" for miktex.
                 if sys.platform == "win32" else
                 ["gs"])
        for e in execs:
            try:
                return impl([e, "--version"], "(.*)", "9")
            except ExecutableNotFoundError:
                pass
        message = "Failed to find a Ghostscript installation"
        raise ExecutableNotFoundError(message)
    elif name == "inkscape":
        try:
            # Try headless option first (needed for Inkscape version < 1.0):
            return impl(["inkscape", "--without-gui", "-V"],
                        "Inkscape ([^ ]*)")
        except ExecutableNotFoundError:
            pass  # Suppress exception chaining.
        # If --without-gui is not accepted, we may be using Inkscape >= 1.0 so
        # try without it:
        return impl(["inkscape", "-V"], "Inkscape ([^ ]*)")
    elif name == "magick":
        path = None
        if sys.platform == "win32":
            # Check the registry to avoid confusing ImageMagick's convert with
            # Windows's builtin convert.exe.
            import winreg
            binpath = ""
            for flag in [0, winreg.KEY_WOW64_32KEY, winreg.KEY_WOW64_64KEY]:
                try:
                    with winreg.OpenKeyEx(
                            winreg.HKEY_LOCAL_MACHINE,
                            r"Software\Imagemagick\Current",
                            0, winreg.KEY_QUERY_VALUE | flag) as hkey:
                        binpath = winreg.QueryValueEx(hkey, "BinPath")[0]
                except OSError:
                    pass
            if binpath:
                for name in ["convert.exe", "magick.exe"]:
                    candidate = Path(binpath, name)
                    if candidate.exists():
                        path = str(candidate)
                        break
        else:
            path = "convert"
        if path is None:
            raise ExecutableNotFoundError(
                "Failed to find an ImageMagick installation")
        return impl([path, "--version"], r"^Version: ImageMagick (\S*)")
    elif name == "pdftops":
        info = impl(["pdftops", "-v"], "^pdftops version (.*)",
                    ignore_exit_code=True)
        if info and not ("3.0" <= info.version
                         # poppler version numbers.
                         or "0.9" <= info.version <= "1.0"):
            raise ExecutableNotFoundError(
                f"You have pdftops version {info.version} but the minimum "
                f"version supported by Matplotlib is 3.0")
        return info
    else:
        raise ValueError("Unknown executable: {!r}".format(name))


@cbook.deprecated("3.2")
def checkdep_ps_distiller(s):
    if not s:
        return False
    try:
        _get_executable_info("gs")
    except ExecutableNotFoundError:
        _log.warning(
            "Setting rcParams['ps.usedistiller'] requires ghostscript.")
        return False
    if s == "xpdf":
        try:
            _get_executable_info("pdftops")
        except ExecutableNotFoundError:
            _log.warning(
                "Setting rcParams['ps.usedistiller'] to 'xpdf' requires xpdf.")
            return False
    return s


def checkdep_usetex(s):
    if not s:
        return False
    if not shutil.which("tex"):
        _log.warning("usetex mode requires TeX.")
        return False
    try:
        _get_executable_info("dvipng")
    except ExecutableNotFoundError:
        _log.warning("usetex mode requires dvipng.")
        return False
    try:
        _get_executable_info("gs")
    except ExecutableNotFoundError:
        _log.warning("usetex mode requires ghostscript.")
        return False
    return True


@cbook.deprecated("3.2", alternative="os.path.expanduser('~')")
@_logged_cached('$HOME=%s')
def get_home():
    """
    Return the user's home directory.

    If the user's home directory cannot be found, return None.
    """
    try:
        return str(Path.home())
    except Exception:
        return None


def _get_xdg_config_dir():
    """
    Return the XDG configuration directory, according to the XDG base
    directory spec:

    https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
    """
    return os.environ.get('XDG_CONFIG_HOME') or str(Path.home() / ".config")


def _get_xdg_cache_dir():
    """
    Return the XDG cache directory, according to the XDG base directory spec:

    https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
    """
    return os.environ.get('XDG_CACHE_HOME') or str(Path.home() / ".cache")


def _get_config_or_cache_dir(xdg_base):
    configdir = os.environ.get('MPLCONFIGDIR')
    if configdir:
        configdir = Path(configdir).resolve()
    elif sys.platform.startswith(('linux', 'freebsd')) and xdg_base:
        configdir = Path(xdg_base, "matplotlib")
    else:
        configdir = Path.home() / ".matplotlib"
    try:
        configdir.mkdir(parents=True, exist_ok=True)
    except OSError:
        pass
    else:
        if os.access(str(configdir), os.W_OK) and configdir.is_dir():
            return str(configdir)
    # If the config or cache directory cannot be created or is not a writable
    # directory, create a temporary one.
    tmpdir = os.environ["MPLCONFIGDIR"] = \
        tempfile.mkdtemp(prefix="matplotlib-")
    atexit.register(shutil.rmtree, tmpdir)
    _log.warning(
        "Matplotlib created a temporary config/cache directory at %s because "
        "the default path (%s) is not a writable directory; it is highly "
        "recommended to set the MPLCONFIGDIR environment variable to a "
        "writable directory, in particular to speed up the import of "
        "Matplotlib and to better support multiprocessing.",
        tmpdir, configdir)
    return tmpdir


@_logged_cached('CONFIGDIR=%s')
def get_configdir():
    """
    Return the string path of the the configuration directory.

    The directory is chosen as follows:

    1. If the MPLCONFIGDIR environment variable is supplied, choose that.
    2. On Linux, follow the XDG specification and look first in
       ``$XDG_CONFIG_HOME``, if defined, or ``$HOME/.config``.  On other
       platforms, choose ``$HOME/.matplotlib``.
    3. If the chosen directory exists and is writable, use that as the
       configuration directory.
    4. Else, create a temporary directory, and use it as the configuration
       directory.
    """
    return _get_config_or_cache_dir(_get_xdg_config_dir())


@_logged_cached('CACHEDIR=%s')
def get_cachedir():
    """
    Return the string path of the cache directory.

    The procedure used to find the directory is the same as for
    _get_config_dir, except using ``$XDG_CACHE_HOME``/``$HOME/.cache`` instead.
    """
    return _get_config_or_cache_dir(_get_xdg_cache_dir())


@_logged_cached('matplotlib data path: %s')
def get_data_path(*, _from_rc=None):
    """Return the path to Matplotlib data."""
    if _from_rc is not None:
        cbook.warn_deprecated(
            "3.2",
            message=("Setting the datapath via matplotlibrc is deprecated "
                     "%(since)s and will be removed %(removal)s."),
            removal='3.4')
        path = Path(_from_rc)
        if path.is_dir():
            return str(path)
        else:
            warnings.warn(f"You passed datapath: {_from_rc!r} in your "
                          f"matplotribrc file ({matplotlib_fname()}). "
                          "However this path does not exist, falling back "
                          "to standard paths.")

    return _get_data_path()


@_logged_cached('(private) matplotlib data path: %s')
def _get_data_path():
    path = Path(__file__).with_name("mpl-data")
    if path.is_dir():
        return str(path)

    cbook.warn_deprecated(
        "3.2", message="Matplotlib installs where the data is not in the "
        "mpl-data subdirectory of the package are deprecated since %(since)s "
        "and support for them will be removed %(removal)s.")

    def get_candidate_paths():
        # setuptools' namespace_packages may hijack this init file
        # so need to try something known to be in Matplotlib, not basemap.
        import matplotlib.afm
        yield Path(matplotlib.afm.__file__).with_name('mpl-data')
        # py2exe zips pure python, so still need special check.
        if getattr(sys, 'frozen', None):
            yield Path(sys.executable).with_name('mpl-data')
            # Try again assuming we need to step up one more directory.
            yield Path(sys.executable).parent.with_name('mpl-data')
            # Try again assuming sys.path[0] is a dir not a exe.
            yield Path(sys.path[0]) / 'mpl-data'

    for path in get_candidate_paths():
        if path.is_dir():
            defaultParams['datapath'][0] = str(path)
            return str(path)

    raise RuntimeError('Could not find the matplotlib data files')


def matplotlib_fname():
    """
    Get the location of the config file.

    The file location is determined in the following order

    - ``$PWD/matplotlibrc``
    - ``$MATPLOTLIBRC`` if it is not a directory
    - ``$MATPLOTLIBRC/matplotlibrc``
    - ``$MPLCONFIGDIR/matplotlibrc``
    - On Linux,
        - ``$XDG_CONFIG_HOME/matplotlib/matplotlibrc`` (if ``$XDG_CONFIG_HOME``
          is defined)
        - or ``$HOME/.config/matplotlib/matplotlibrc`` (if ``$XDG_CONFIG_HOME``
          is not defined)
    - On other platforms,
      - ``$HOME/.matplotlib/matplotlibrc`` if ``$HOME`` is defined
    - Lastly, it looks in ``$MATPLOTLIBDATA/matplotlibrc``, which should always
      exist.
    """

    def gen_candidates():
        yield os.path.join(os.getcwd(), 'matplotlibrc')
        try:
            matplotlibrc = os.environ['MATPLOTLIBRC']
        except KeyError:
            pass
        else:
            yield matplotlibrc
            yield os.path.join(matplotlibrc, 'matplotlibrc')
        yield os.path.join(get_configdir(), 'matplotlibrc')
        yield os.path.join(_get_data_path(), 'matplotlibrc')

    for fname in gen_candidates():
        if os.path.exists(fname) and not os.path.isdir(fname):
            return fname

    raise RuntimeError("Could not find matplotlibrc file; your Matplotlib "
                       "install is broken")


# rcParams deprecated and automatically mapped to another key.
# Values are tuples of (version, new_name, f_old2new, f_new2old).
_deprecated_map = {}

# rcParams deprecated; some can manually be mapped to another key.
# Values are tuples of (version, new_name_or_None).
_deprecated_ignore_map = {
}

# rcParams deprecated; can use None to suppress warnings; remain actually
# listed in the rcParams (not included in _all_deprecated).
# Values are tuples of (version,)
_deprecated_remain_as_none = {
    'datapath': ('3.2.1',),
    'animation.avconv_path': ('3.3',),
    'animation.avconv_args': ('3.3',),
    'animation.html_args': ('3.3',),
    'mathtext.fallback_to_cm': ('3.3',),
    'keymap.all_axes': ('3.3',),
    'savefig.jpeg_quality': ('3.3',),
    'text.latex.preview': ('3.3',),
}


_all_deprecated = {*_deprecated_map, *_deprecated_ignore_map}


class RcParams(MutableMapping, dict):
    """
    A dictionary object including validation.

    Validating functions are defined and associated with rc parameters in
    :mod:`matplotlib.rcsetup`.

    See Also
    --------
    :ref:`customizing-with-matplotlibrc-files`
    """

    validate = rcsetup._validators

    # validate values on the way in
    def __init__(self, *args, **kwargs):
        self.update(*args, **kwargs)

    def __setitem__(self, key, val):
        try:
            if key in _deprecated_map:
                version, alt_key, alt_val, inverse_alt = _deprecated_map[key]
                cbook.warn_deprecated(
                    version, name=key, obj_type="rcparam", alternative=alt_key)
                key = alt_key
                val = alt_val(val)
            elif key in _deprecated_remain_as_none and val is not None:
                version, = _deprecated_remain_as_none[key]
                cbook.warn_deprecated(
                    version, name=key, obj_type="rcparam")
            elif key in _deprecated_ignore_map:
                version, alt_key = _deprecated_ignore_map[key]
                cbook.warn_deprecated(
                    version, name=key, obj_type="rcparam", alternative=alt_key)
                return
            elif key == 'backend':
                if val is rcsetup._auto_backend_sentinel:
                    if 'backend' in self:
                        return
            try:
                cval = self.validate[key](val)
            except ValueError as ve:
                raise ValueError(f"Key {key}: {ve}") from None
            dict.__setitem__(self, key, cval)
        except KeyError as err:
            raise KeyError(
                f"{key} is not a valid rc parameter (see rcParams.keys() for "
                f"a list of valid parameters)") from err

    def __getitem__(self, key):
        if key in _deprecated_map:
            version, alt_key, alt_val, inverse_alt = _deprecated_map[key]
            cbook.warn_deprecated(
                version, name=key, obj_type="rcparam", alternative=alt_key)
            return inverse_alt(dict.__getitem__(self, alt_key))

        elif key in _deprecated_ignore_map:
            version, alt_key = _deprecated_ignore_map[key]
            cbook.warn_deprecated(
                version, name=key, obj_type="rcparam", alternative=alt_key)
            return dict.__getitem__(self, alt_key) if alt_key else None

        elif key == "backend":
            val = dict.__getitem__(self, key)
            if val is rcsetup._auto_backend_sentinel:
                from matplotlib import pyplot as plt
                plt.switch_backend(rcsetup._auto_backend_sentinel)

        elif key == "datapath":
            return get_data_path()

        return dict.__getitem__(self, key)

    def __repr__(self):
        class_name = self.__class__.__name__
        indent = len(class_name) + 1
        with cbook._suppress_matplotlib_deprecation_warning():
            repr_split = pprint.pformat(dict(self), indent=1,
                                        width=80 - indent).split('\n')
        repr_indented = ('\n' + ' ' * indent).join(repr_split)
        return '{}({})'.format(class_name, repr_indented)

    def __str__(self):
        return '\n'.join(map('{0[0]}: {0[1]}'.format, sorted(self.items())))

    def __iter__(self):
        """Yield sorted list of keys."""
        with cbook._suppress_matplotlib_deprecation_warning():
            yield from sorted(dict.__iter__(self))

    def __len__(self):
        return dict.__len__(self)

    def find_all(self, pattern):
        """
        Return the subset of this RcParams dictionary whose keys match,
        using :func:`re.search`, the given ``pattern``.

        .. note::

            Changes to the returned dictionary are *not* propagated to
            the parent RcParams dictionary.

        """
        pattern_re = re.compile(pattern)
        return RcParams((key, value)
                        for key, value in self.items()
                        if pattern_re.search(key))

    def copy(self):
        return {k: dict.__getitem__(self, k) for k in self}


def rc_params(fail_on_error=False):
    """Construct a `RcParams` instance from the default Matplotlib rc file."""
    return rc_params_from_file(matplotlib_fname(), fail_on_error)


URL_REGEX = re.compile(r'^http://|^https://|^ftp://|^file:')


def is_url(filename):
    """Return True if string is an http, ftp, or file URL path."""
    return URL_REGEX.match(filename) is not None


@functools.lru_cache()
def _get_ssl_context():
    try:
        import certifi
    except ImportError:
        _log.debug("Could not import certifi.")
        return None
    import ssl
    return ssl.create_default_context(cafile=certifi.where())


@contextlib.contextmanager
def _open_file_or_url(fname):
    if not isinstance(fname, Path) and is_url(fname):
        import urllib.request
        ssl_ctx = _get_ssl_context()
        if ssl_ctx is None:
            _log.debug(
                "Could not get certifi ssl context, https may not work."
            )
        with urllib.request.urlopen(fname, context=ssl_ctx) as f:
            yield (line.decode('utf-8') for line in f)
    else:
        fname = os.path.expanduser(fname)
        encoding = locale.getpreferredencoding(do_setlocale=False)
        if encoding is None:
            encoding = "utf-8"
        with open(fname, encoding=encoding) as f:
            yield f


def _rc_params_in_file(fname, transform=lambda x: x, fail_on_error=False):
    """
    Construct a `RcParams` instance from file *fname*.

    Unlike `rc_params_from_file`, the configuration class only contains the
    parameters specified in the file (i.e. default values are not filled in).

    Parameters
    ----------
    fname : path-like
        The loaded file.
    transform : callable, default: the identity function
        A function called on each individual line of the file to transform it,
        before further parsing.
    fail_on_error : bool, default: False
        Whether invalid entries should result in an exception or a warning.
    """
    rc_temp = {}
    with _open_file_or_url(fname) as fd:
        try:
            for line_no, line in enumerate(fd, 1):
                line = transform(line)
                strippedline = line.split('#', 1)[0].strip()
                if not strippedline:
                    continue
                tup = strippedline.split(':', 1)
                if len(tup) != 2:
                    _log.warning('Missing colon in file %r, line %d (%r)',
                                 fname, line_no, line.rstrip('\n'))
                    continue
                key, val = tup
                key = key.strip()
                val = val.strip()
                if key in rc_temp:
                    _log.warning('Duplicate key in file %r, line %d (%r)',
                                 fname, line_no, line.rstrip('\n'))
                rc_temp[key] = (val, line, line_no)
        except UnicodeDecodeError:
            _log.warning('Cannot decode configuration file %s with encoding '
                         '%s, check LANG and LC_* variables.',
                         fname,
                         locale.getpreferredencoding(do_setlocale=False)
                         or 'utf-8 (default)')
            raise

    config = RcParams()

    for key, (val, line, line_no) in rc_temp.items():
        if key in rcsetup._validators:
            if fail_on_error:
                config[key] = val  # try to convert to proper type or raise
            else:
                try:
                    config[key] = val  # try to convert to proper type or skip
                except Exception as msg:
                    _log.warning('Bad value in file %r, line %d (%r): %s',
                                 fname, line_no, line.rstrip('\n'), msg)
        elif key in _deprecated_ignore_map:
            version, alt_key = _deprecated_ignore_map[key]
            cbook.warn_deprecated(
                version, name=key, alternative=alt_key,
                addendum="Please update your matplotlibrc.")
        else:
            version = 'master' if '.post' in __version__ else f'v{__version__}'
            _log.warning("""
Bad key %(key)s in file %(fname)s, line %(line_no)s (%(line)r)
You probably need to get an updated matplotlibrc file from
https://github.com/matplotlib/matplotlib/blob/%(version)s/matplotlibrc.template
or from the matplotlib source distribution""",
                         dict(key=key, fname=fname, line_no=line_no,
                              line=line.rstrip('\n'), version=version))
    return config


def rc_params_from_file(fname, fail_on_error=False, use_default_template=True):
    """
    Construct a `RcParams` from file *fname*.

    Parameters
    ----------
    fname : str or path-like
        A file with Matplotlib rc settings.
    fail_on_error : bool
        If True, raise an error when the parser fails to convert a parameter.
    use_default_template : bool
        If True, initialize with default parameters before updating with those
        in the given file. If False, the configuration class only contains the
        parameters specified in the file. (Useful for updating dicts.)
    """
    config_from_file = _rc_params_in_file(fname, fail_on_error=fail_on_error)

    if not use_default_template:
        return config_from_file

    with cbook._suppress_matplotlib_deprecation_warning():
        config = RcParams({**rcParamsDefault, **config_from_file})

    with cbook._suppress_matplotlib_deprecation_warning():
        if config['datapath'] is None:
            config['datapath'] = _get_data_path()
        else:
            config['datapath'] = get_data_path(_from_rc=config['datapath'])

    if "".join(config['text.latex.preamble']):
        _log.info("""
*****************************************************************
You have the following UNSUPPORTED LaTeX preamble customizations:
%s
Please do not ask for support with these customizations active.
*****************************************************************
""", '\n'.join(config['text.latex.preamble']))
    _log.debug('loaded rc file %s', fname)

    return config


# When constructing the global instances, we need to perform certain updates
# by explicitly calling the superclass (dict.update, dict.items) to avoid
# triggering resolution of _auto_backend_sentinel.
rcParamsDefault = _rc_params_in_file(
    cbook._get_data_path("matplotlibrc"),
    # Strip leading comment.
    transform=lambda line: line[1:] if line.startswith("#") else line,
    fail_on_error=True)
dict.update(rcParamsDefault, rcsetup._hardcoded_defaults)
rcParams = RcParams()  # The global instance.
dict.update(rcParams, dict.items(rcParamsDefault))
dict.update(rcParams, _rc_params_in_file(matplotlib_fname()))
with cbook._suppress_matplotlib_deprecation_warning():
    rcParamsOrig = RcParams(rcParams.copy())
    # This also checks that all rcParams are indeed listed in the template.
    # Assiging to rcsetup.defaultParams is left only for backcompat.
    defaultParams = rcsetup.defaultParams = {
        # We want to resolve deprecated rcParams, but not backend...
        key: [(rcsetup._auto_backend_sentinel if key == "backend" else
               rcParamsDefault[key]),
              validator]
        for key, validator in rcsetup._validators.items()}
if rcParams['axes.formatter.use_locale']:
    locale.setlocale(locale.LC_ALL, '')


def rc(group, **kwargs):
    """
    Set the current `.rcParams`.  *group* is the grouping for the rc, e.g.,
    for ``lines.linewidth`` the group is ``lines``, for
    ``axes.facecolor``, the group is ``axes``, and so on.  Group may
    also be a list or tuple of group names, e.g., (*xtick*, *ytick*).
    *kwargs* is a dictionary attribute name/value pairs, e.g.,::

      rc('lines', linewidth=2, color='r')

    sets the current `.rcParams` and is equivalent to::

      rcParams['lines.linewidth'] = 2
      rcParams['lines.color'] = 'r'

    The following aliases are available to save typing for interactive users:

    =====   =================
    Alias   Property
    =====   =================
    'lw'    'linewidth'
    'ls'    'linestyle'
    'c'     'color'
    'fc'    'facecolor'
    'ec'    'edgecolor'
    'mew'   'markeredgewidth'
    'aa'    'antialiased'
    =====   =================

    Thus you could abbreviate the above call as::

          rc('lines', lw=2, c='r')

    Note you can use python's kwargs dictionary facility to store
    dictionaries of default parameters.  e.g., you can customize the
    font rc as follows::

      font = {'family' : 'monospace',
              'weight' : 'bold',
              'size'   : 'larger'}
      rc('font', **font)  # pass in the font dict as kwargs

    This enables you to easily switch between several configurations.  Use
    ``matplotlib.style.use('default')`` or :func:`~matplotlib.rcdefaults` to
    restore the default `.rcParams` after changes.

    Notes
    -----
    Similar functionality is available by using the normal dict interface, i.e.
    ``rcParams.update({"lines.linewidth": 2, ...})`` (but ``rcParams.update``
    does not support abbreviations or grouping).
    """

    aliases = {
        'lw':  'linewidth',
        'ls':  'linestyle',
        'c':   'color',
        'fc':  'facecolor',
        'ec':  'edgecolor',
        'mew': 'markeredgewidth',
        'aa':  'antialiased',
        }

    if isinstance(group, str):
        group = (group,)
    for g in group:
        for k, v in kwargs.items():
            name = aliases.get(k) or k
            key = '%s.%s' % (g, name)
            try:
                rcParams[key] = v
            except KeyError as err:
                raise KeyError(('Unrecognized key "%s" for group "%s" and '
                                'name "%s"') % (key, g, name)) from err


def rcdefaults():
    """
    Restore the `.rcParams` from Matplotlib's internal default style.

    Style-blacklisted `.rcParams` (defined in
    `matplotlib.style.core.STYLE_BLACKLIST`) are not updated.

    See Also
    --------
    matplotlib.rc_file_defaults
        Restore the `.rcParams` from the rc file originally loaded by
        Matplotlib.
    matplotlib.style.use
        Use a specific style file.  Call ``style.use('default')`` to restore
        the default style.
    """
    # Deprecation warnings were already handled when creating rcParamsDefault,
    # no need to reemit them here.
    with cbook._suppress_matplotlib_deprecation_warning():
        from .style.core import STYLE_BLACKLIST
        rcParams.clear()
        rcParams.update({k: v for k, v in rcParamsDefault.items()
                         if k not in STYLE_BLACKLIST})


def rc_file_defaults():
    """
    Restore the `.rcParams` from the original rc file loaded by Matplotlib.

    Style-blacklisted `.rcParams` (defined in
    `matplotlib.style.core.STYLE_BLACKLIST`) are not updated.
    """
    # Deprecation warnings were already handled when creating rcParamsOrig, no
    # need to reemit them here.
    with cbook._suppress_matplotlib_deprecation_warning():
        from .style.core import STYLE_BLACKLIST
        rcParams.update({k: rcParamsOrig[k] for k in rcParamsOrig
                         if k not in STYLE_BLACKLIST})


def rc_file(fname, *, use_default_template=True):
    """
    Update `.rcParams` from file.

    Style-blacklisted `.rcParams` (defined in
    `matplotlib.style.core.STYLE_BLACKLIST`) are not updated.

    Parameters
    ----------
    fname : str or path-like
        A file with Matplotlib rc settings.

    use_default_template : bool
        If True, initialize with default parameters before updating with those
        in the given file. If False, the current configuration persists
        and only the parameters specified in the file are updated.
    """
    # Deprecation warnings were already handled in rc_params_from_file, no need
    # to reemit them here.
    with cbook._suppress_matplotlib_deprecation_warning():
        from .style.core import STYLE_BLACKLIST
        rc_from_file = rc_params_from_file(
            fname, use_default_template=use_default_template)
        rcParams.update({k: rc_from_file[k] for k in rc_from_file
                         if k not in STYLE_BLACKLIST})


@contextlib.contextmanager
def rc_context(rc=None, fname=None):
    """
    Return a context manager for temporarily changing rcParams.

    Parameters
    ----------
    rc : dict
        The rcParams to temporarily set.
    fname : str or path-like
        A file with Matplotlib rc settings. If both *fname* and *rc* are given,
        settings from *rc* take precedence.

    See Also
    --------
    :ref:`customizing-with-matplotlibrc-files`

    Examples
    --------
    Passing explicit values via a dict::

        with mpl.rc_context({'interactive': False}):
            fig, ax = plt.subplots()
            ax.plot(range(3), range(3))
            fig.savefig('example.png')
            plt.close(fig)

    Loading settings from a file::

         with mpl.rc_context(fname='print.rc'):
             plt.plot(x, y)  # uses 'print.rc'

    """
    orig = rcParams.copy()
    try:
        if fname:
            rc_file(fname)
        if rc:
            rcParams.update(rc)
        yield
    finally:
        dict.update(rcParams, orig)  # Revert to the original rcs.


def use(backend, *, force=True):
    """
    Select the backend used for rendering and GUI integration.

    Parameters
    ----------
    backend : str
        The backend to switch to.  This can either be one of the standard
        backend names, which are case-insensitive:

        - interactive backends:
          GTK3Agg, GTK3Cairo, MacOSX, nbAgg,
          Qt4Agg, Qt4Cairo, Qt5Agg, Qt5Cairo,
          TkAgg, TkCairo, WebAgg, WX, WXAgg, WXCairo

        - non-interactive backends:
          agg, cairo, pdf, pgf, ps, svg, template

        or a string of the form: ``module://my.module.name``.

    force : bool, default: True
        If True (the default), raise an `ImportError` if the backend cannot be
        set up (either because it fails to import, or because an incompatible
        GUI interactive framework is already running); if False, ignore the
        failure.

    See Also
    --------
    :ref:`backends`
    matplotlib.get_backend
    """
    name = validate_backend(backend)
    # we need to use the base-class method here to avoid (prematurely)
    # resolving the "auto" backend setting
    if dict.__getitem__(rcParams, 'backend') == name:
        # Nothing to do if the requested backend is already set
        pass
    else:
        # if pyplot is not already imported, do not import it.  Doing
        # so may trigger a `plt.switch_backend` to the _default_ backend
        # before we get a chance to change to the one the user just requested
        plt = sys.modules.get('matplotlib.pyplot')
        # if pyplot is imported, then try to change backends
        if plt is not None:
            try:
                # we need this import check here to re-raise if the
                # user does not have the libraries to support their
                # chosen backend installed.
                plt.switch_backend(name)
            except ImportError:
                if force:
                    raise
        # if we have not imported pyplot, then we can set the rcParam
        # value which will be respected when the user finally imports
        # pyplot
        else:
            rcParams['backend'] = backend
    # if the user has asked for a given backend, do not helpfully
    # fallback
    rcParams['backend_fallback'] = False


if os.environ.get('MPLBACKEND'):
    rcParams['backend'] = os.environ.get('MPLBACKEND')


def get_backend():
    """
    Return the name of the current backend.

    See Also
    --------
    matplotlib.use
    """
    return rcParams['backend']


def interactive(b):
    """
    Set whether to redraw after every plotting command (e.g. `.pyplot.xlabel`).
    """
    rcParams['interactive'] = b


def is_interactive():
    """Return whether to redraw after every plotting command."""
    return rcParams['interactive']


default_test_modules = [
    'matplotlib.tests',
    'mpl_toolkits.tests',
]


def _init_tests():
    # The version of FreeType to install locally for running the
    # tests.  This must match the value in `setupext.py`
    LOCAL_FREETYPE_VERSION = '2.6.1'

    from matplotlib import ft2font
    if (ft2font.__freetype_version__ != LOCAL_FREETYPE_VERSION or
            ft2font.__freetype_build_type__ != 'local'):
        _log.warning(
            f"Matplotlib is not built with the correct FreeType version to "
            f"run tests.  Rebuild without setting system_freetype=1 in "
            f"setup.cfg.  Expect many image comparison failures below.  "
            f"Expected freetype version {LOCAL_FREETYPE_VERSION}.  "
            f"Found freetype version {ft2font.__freetype_version__}.  "
            "Freetype build type is {}local".format(
                "" if ft2font.__freetype_build_type__ == 'local' else "not "))


@cbook._delete_parameter("3.2", "switch_backend_warn")
@cbook._delete_parameter("3.3", "recursionlimit")
def test(verbosity=None, coverage=False, switch_backend_warn=True,
         recursionlimit=0, **kwargs):
    """Run the matplotlib test suite."""

    try:
        import pytest
    except ImportError:
        print("matplotlib.test requires pytest to run.")
        return -1

    if not os.path.isdir(os.path.join(os.path.dirname(__file__), 'tests')):
        print("Matplotlib test data is not installed")
        return -1

    old_backend = get_backend()
    old_recursionlimit = sys.getrecursionlimit()
    try:
        use('agg')
        if recursionlimit:
            sys.setrecursionlimit(recursionlimit)

        args = kwargs.pop('argv', [])
        provide_default_modules = True
        use_pyargs = True
        for arg in args:
            if any(arg.startswith(module_path)
                   for module_path in default_test_modules):
                provide_default_modules = False
                break
            if os.path.exists(arg):
                provide_default_modules = False
                use_pyargs = False
                break
        if use_pyargs:
            args += ['--pyargs']
        if provide_default_modules:
            args += default_test_modules

        if coverage:
            args += ['--cov']

        if verbosity:
            args += ['-' + 'v' * verbosity]

        retcode = pytest.main(args, **kwargs)
    finally:
        if old_backend.lower() != 'agg':
            use(old_backend)
        if recursionlimit:
            sys.setrecursionlimit(old_recursionlimit)

    return retcode


test.__test__ = False  # pytest: this function is not a test


def _replacer(data, value):
    """
    Either returns ``data[value]`` or passes ``data`` back, converts either to
    a sequence.
    """
    try:
        # if key isn't a string don't bother
        if isinstance(value, str):
            # try to use __getitem__
            value = data[value]
    except Exception:
        # key does not exist, silently fall back to key
        pass
    return sanitize_sequence(value)


def _label_from_arg(y, default_name):
    try:
        return y.name
    except AttributeError:
        if isinstance(default_name, str):
            return default_name
    return None


_DATA_DOC_TITLE = """

Notes
-----
"""

_DATA_DOC_APPENDIX = """

.. note::
    In addition to the above described arguments, this function can take
    a *data* keyword argument. If such a *data* argument is given,
{replaced}

    Objects passed as **data** must support item access (``data[s]``) and
    membership test (``s in data``).
"""


def _add_data_doc(docstring, replace_names):
    """
    Add documentation for a *data* field to the given docstring.

    Parameters
    ----------
    docstring : str
        The input docstring.
    replace_names : list of str or None
        The list of parameter names which arguments should be replaced by
        ``data[name]`` (if ``data[name]`` does not throw an exception).  If
        None, replacement is attempted for all arguments.

    Returns
    -------
    str
        The augmented docstring.
    """
    if (docstring is None
            or replace_names is not None and len(replace_names) == 0):
        return docstring
    docstring = inspect.cleandoc(docstring)
    repl = (
        ("    every other argument can also be string ``s``, which is\n"
         "    interpreted as ``data[s]`` (unless this raises an exception).")
        if replace_names is None else
        ("    the following arguments can also be string ``s``, which is\n"
         "    interpreted as ``data[s]`` (unless this raises an exception):\n"
         "    " + ", ".join(map("*{}*".format, replace_names))) + ".")
    addendum = _DATA_DOC_APPENDIX.format(replaced=repl)
    if _DATA_DOC_TITLE not in docstring:
        addendum = _DATA_DOC_TITLE + addendum
    return docstring + addendum


def _preprocess_data(func=None, *, replace_names=None, label_namer=None):
    """
    A decorator to add a 'data' kwarg to a function.

    When applied::

        @_preprocess_data()
        def func(ax, *args, **kwargs): ...

    the signature is modified to ``decorated(ax, *args, data=None, **kwargs)``
    with the following behavior:

    - if called with ``data=None``, forward the other arguments to ``func``;
    - otherwise, *data* must be a mapping; for any argument passed in as a
      string ``name``, replace the argument by ``data[name]`` (if this does not
      throw an exception), then forward the arguments to ``func``.

    In either case, any argument that is a `MappingView` is also converted to a
    list.

    Parameters
    ----------
    replace_names : list of str or None, default: None
        The list of parameter names for which lookup into *data* should be
        attempted. If None, replacement is attempted for all arguments.
    label_namer : str, default: None
        If set e.g. to "namer" (which must be a kwarg in the function's
        signature -- not as ``**kwargs``), if the *namer* argument passed in is
        a (string) key of *data* and no *label* kwarg is passed, then use the
        (string) value of the *namer* as *label*. ::

            @_preprocess_data(label_namer="foo")
            def func(foo, label=None): ...

            func("key", data={"key": value})
            # is equivalent to
            func.__wrapped__(value, label="key")
    """

    if func is None:  # Return the actual decorator.
        return functools.partial(
            _preprocess_data,
            replace_names=replace_names, label_namer=label_namer)

    sig = inspect.signature(func)
    varargs_name = None
    varkwargs_name = None
    arg_names = []
    params = list(sig.parameters.values())
    for p in params:
        if p.kind is Parameter.VAR_POSITIONAL:
            varargs_name = p.name
        elif p.kind is Parameter.VAR_KEYWORD:
            varkwargs_name = p.name
        else:
            arg_names.append(p.name)
    data_param = Parameter("data", Parameter.KEYWORD_ONLY, default=None)
    if varkwargs_name:
        params.insert(-1, data_param)
    else:
        params.append(data_param)
    new_sig = sig.replace(parameters=params)
    arg_names = arg_names[1:]  # remove the first "ax" / self arg

    assert {*arg_names}.issuperset(replace_names or []) or varkwargs_name, (
        "Matplotlib internal error: invalid replace_names ({!r}) for {!r}"
        .format(replace_names, func.__name__))
    assert label_namer is None or label_namer in arg_names, (
        "Matplotlib internal error: invalid label_namer ({!r}) for {!r}"
        .format(label_namer, func.__name__))

    @functools.wraps(func)
    def inner(ax, *args, data=None, **kwargs):
        if data is None:
            return func(ax, *map(sanitize_sequence, args), **kwargs)

        bound = new_sig.bind(ax, *args, **kwargs)
        auto_label = (bound.arguments.get(label_namer)
                      or bound.kwargs.get(label_namer))

        for k, v in bound.arguments.items():
            if k == varkwargs_name:
                for k1, v1 in v.items():
                    if replace_names is None or k1 in replace_names:
                        v[k1] = _replacer(data, v1)
            elif k == varargs_name:
                if replace_names is None:
                    bound.arguments[k] = tuple(_replacer(data, v1) for v1 in v)
            else:
                if replace_names is None or k in replace_names:
                    bound.arguments[k] = _replacer(data, v)

        new_args = bound.args
        new_kwargs = bound.kwargs

        args_and_kwargs = {**bound.arguments, **bound.kwargs}
        if label_namer and "label" not in args_and_kwargs:
            new_kwargs["label"] = _label_from_arg(
                args_and_kwargs.get(label_namer), auto_label)

        return func(*new_args, **new_kwargs)

    inner.__doc__ = _add_data_doc(inner.__doc__, replace_names)
    inner.__signature__ = new_sig
    return inner


_log.debug('matplotlib version %s', __version__)
_log.debug('interactive is %s', is_interactive())
_log.debug('platform is %s', sys.platform)
_log.debug('loaded modules: %s', list(sys.modules))