"""
This is an object-orient plotting library.

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

    from pylab import *

or using ipython::

    ipython -pylab

For the most part, direct use of the object-oriented library is
encouraged when programming rather than working interactively.  The
exceptions are the pylab commands :func:`~matplotlib.pyplot.figure`,
:func:`~matplotlib.pyplot.subplot`,
:func:`~matplotlib.backends.backend_qt4agg.show`, and
:func:`~pyplot.savefig`, which can greatly simplify scripting.

Modules include:

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

    :mod:`matplotlib.figure`
        defines the :class:`~matplotlib.figure.Figure` class.

    :mod:`matplotlib.artist`
        defines the :class:`~matplotlib.artist.Artist` base class for
        all classes that draw things.

    :mod:`matplotlib.lines`
        defines the :class:`~matplotlib.lines.Line2D` class for
        drawing lines and markers

    :mod:`matplotlib.patches`
        defines classes for drawing polygons

    :mod:`matplotlib.text`
        defines the :class:`~matplotlib.text.Text`,
        :class:`~matplotlib.text.TextWithDash`, and
        :class:`~matplotlib.text.Annotate` classes

    :mod:`matplotlib.image`
        defines the :class:`~matplotlib.image.AxesImage` and
        :class:`~matplotlib.image.FigureImage` classes

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

    :mod:`matplotlib.colors`
        classes for interpreting color specifications and for making
        colormaps

    :mod:`matplotlib.cm`
        colormaps and the :class:`~matplotlib.image.ScalarMappable`
        mixin class for providing color mapping functionality to other
        classes

    :mod:`matplotlib.ticker`
        classes for calculating tick mark locations and for formatting
        tick labels

    :mod:`matplotlib.backends`
        a subpackage with modules for various gui libraries and output
        formats

The base matplotlib namespace includes:

    :data:`~matplotlib.rcParams`
        a global dictionary of default configuration settings.  It is
        initialized by code which may be overridded by a matplotlibrc
        file.

    :func:`~matplotlib.rc`
        a function for setting groups of rcParams values

    :func:`~matplotlib.use`
        a function for setting the matplotlib backend.  If used, this
        function must be called immediately after importing matplotlib
        for the first time.  In particular, it must be called
        **before** importing pylab (if pylab is imported).

matplotlib is written by John D. Hunter (jdh2358 at gmail.com) and a
host of others.
"""
from __future__ import generators

__version__  = '0.98.5.3'
__revision__ = '$Revision: 6890 $'
__date__     = '$Date: 2009-02-08 14:29:42 -0600 (Sun, 08 Feb 2009) $'

import os, re, shutil, subprocess, sys, warnings
import distutils.sysconfig
import distutils.version


NEWCONFIG = False


# Needed for toolkit setuptools support
if 0:
    try:
        __import__('pkg_resources').declare_namespace(__name__)
    except ImportError:
        pass # must not have setuptools

if not hasattr(sys, 'argv'):  # for modpython
    sys.argv = ['modpython']

"""
Manage user customizations through a rc file.

The default file location is given in the following order

  - environment variable MATPLOTLIBRC

  - HOME/.matplotlib/matplotlibrc if HOME is defined

  - PATH/matplotlibrc where PATH is the return value of
    get_data_path()
"""

import sys, os, tempfile

from rcsetup import defaultParams, validate_backend, validate_toolbar
from rcsetup import validate_cairo_format

major, minor1, minor2, s, tmp = sys.version_info
_python24 = major>=2 and minor1>=4

# the havedate check was a legacy from old matplotlib which preceeded
# datetime support
_havedate = True

#try:
#    import pkg_resources # pkg_resources is part of setuptools
#except ImportError: _have_pkg_resources = False
#else: _have_pkg_resources = True

if not _python24:
    raise ImportError('matplotlib requires Python 2.4 or later')

import numpy
nn = numpy.__version__.split('.')
if not (int(nn[0]) >= 1 and int(nn[1]) >= 1):
    raise ImportError(
            'numpy 1.1 or later is required; you have %s' % numpy.__version__)

def is_string_like(obj):
    if hasattr(obj, 'shape'): return 0
    try: obj + ''
    except (TypeError, ValueError): return 0
    return 1


def _is_writable_dir(p):
    """
    p is a string pointing to a putative writable dir -- return True p
    is such a string, else False
    """
    try: p + ''  # test is string like
    except TypeError: return False
    try:
        t = tempfile.TemporaryFile(dir=p)
        t.write('1')
        t.close()
    except OSError: return False
    else: return True

class Verbose:
    """
    A class to handle reporting.  Set the fileo attribute to any file
    instance to handle the output.  Default is sys.stdout
    """
    levels = ('silent', 'helpful', 'debug', 'debug-annoying')
    vald = dict( [(level, i) for i,level in enumerate(levels)])

    # parse the verbosity from the command line; flags look like
    # --verbose-silent or --verbose-helpful
    _commandLineVerbose = None

    for arg in sys.argv[1:]:
        if not arg.startswith('--verbose-'): continue
        _commandLineVerbose = arg[10:]

    def __init__(self):
        self.set_level('silent')
        self.fileo = sys.stdout

    def set_level(self, level):
        'set the verbosity to one of the Verbose.levels strings'

        if self._commandLineVerbose is not None:
            level = self._commandLineVerbose
        if level not in self.levels:
            raise ValueError('Illegal verbose string "%s".  Legal values are %s'%(level, self.levels))
        self.level = level

    def set_fileo(self, fname):
        std = {
            'sys.stdout': sys.stdout,
            'sys.stderr': sys.stderr,
        }
        if fname in std:
            self.fileo = std[fname]
        else:
            try:
                fileo = file(fname, 'w')
            except IOError:
                raise ValueError('Verbose object could not open log file "%s" for writing.\nCheck your matplotlibrc verbose.fileo setting'%fname)
            else:
                self.fileo = fileo

    def report(self, s, level='helpful'):
        """
        print message s to self.fileo if self.level>=level.  Return
        value indicates whether a message was issued

        """
        if self.ge(level):
            print >>self.fileo, s
            return True
        return False

    def wrap(self, fmt, func, level='helpful', always=True):
        """
        return a callable function that wraps func and reports it
        output through the verbose handler if current verbosity level
        is higher than level

        if always is True, the report will occur on every function
        call; otherwise only on the first time the function is called
        """
        assert callable(func)
        def wrapper(*args, **kwargs):
            ret = func(*args, **kwargs)

            if (always or not wrapper._spoke):
                spoke = self.report(fmt%ret, level)
                if not wrapper._spoke: wrapper._spoke = spoke
            return ret
        wrapper._spoke = False
        wrapper.__doc__ = func.__doc__
        return wrapper

    def ge(self, level):
        'return true if self.level is >= level'
        return self.vald[self.level]>=self.vald[level]


verbose=Verbose()


def checkdep_dvipng():
    try:
        s = subprocess.Popen(['dvipng','-version'], stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        line = s.stdout.readlines()[1]
        v = line.split()[-1]
        return v
    except (IndexError, ValueError, OSError):
        return None

def checkdep_ghostscript():
    try:
        if sys.platform == 'win32':
            command_args = ['gswin32c', '--version']
        else:
            command_args = ['gs', '--version']
        s = subprocess.Popen(command_args, stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        v = s.stdout.read()[:-1]
        return v
    except (IndexError, ValueError, OSError):
        return None

def checkdep_tex():
    try:
        s = subprocess.Popen(['tex','-version'], stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        line = s.stdout.readlines()[0]
        pattern = '3\.1\d+'
        match = re.search(pattern, line)
        v = match.group(0)
        return v
    except (IndexError, ValueError, AttributeError, OSError):
        return None

def checkdep_pdftops():
    try:
        s = subprocess.Popen(['pdftops','-v'], stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
        for line in s.stderr:
            if 'version' in line:
                v = line.split()[-1]
        return v
    except (IndexError, ValueError, UnboundLocalError, OSError):
        return None

def compare_versions(a, b):
    "return True if a is greater than or equal to b"
    if a:
        a = distutils.version.LooseVersion(a)
        b = distutils.version.LooseVersion(b)
        if a>=b: return True
        else: return False
    else: return False

def checkdep_ps_distiller(s):
    if not s:
        return False

    flag = True
    gs_req = '7.07'
    gs_sugg = '7.07'
    gs_v = checkdep_ghostscript()
    if compare_versions(gs_v, gs_sugg): pass
    elif compare_versions(gs_v, gs_req):
        verbose.report(('ghostscript-%s found. ghostscript-%s or later '
                        'is recommended to use the ps.usedistiller option.') % (gs_v, gs_sugg))
    else:
        flag = False
        warnings.warn(('matplotlibrc ps.usedistiller option can not be used '
                       'unless ghostscript-%s or later is installed on your system') % gs_req)

    if s == 'xpdf':
        pdftops_req = '3.0'
        pdftops_req_alt = '0.9' # poppler version numbers, ugh
        pdftops_v = checkdep_pdftops()
        if compare_versions(pdftops_v, pdftops_req):
            pass
        elif compare_versions(pdftops_v, pdftops_req_alt) and not \
            compare_versions(pdftops_v, '1.0'):
            pass
        else:
            flag = False
            warnings.warn(('matplotlibrc ps.usedistiller can not be set to '
                           'xpdf unless xpdf-%s or later is installed on your system') % pdftops_req)

    if flag:
        return s
    else:
        return False

def checkdep_usetex(s):
    if not s:
        return False

    tex_req = '3.1415'
    gs_req = '7.07'
    gs_sugg = '7.07'
    dvipng_req = '1.5'
    flag = True

    tex_v = checkdep_tex()
    if compare_versions(tex_v, tex_req): pass
    else:
        flag = False
        warnings.warn(('matplotlibrc text.usetex option can not be used '
                       'unless TeX-%s or later is '
                       'installed on your system') % tex_req)

    dvipng_v = checkdep_dvipng()
    if compare_versions(dvipng_v, dvipng_req): pass
    else:
        flag = False
        warnings.warn( 'matplotlibrc text.usetex can not be used with *Agg '
                       'backend unless dvipng-1.5 or later is '
                       'installed on your system')

    gs_v = checkdep_ghostscript()
    if compare_versions(gs_v, gs_sugg): pass
    elif compare_versions(gs_v, gs_req):
        verbose.report(('ghostscript-%s found. ghostscript-%s or later is '
                        'recommended for use with the text.usetex '
                        'option.') % (gs_v, gs_sugg))
    else:
        flag = False
        warnings.warn(('matplotlibrc text.usetex can not be used '
                       'unless ghostscript-%s or later is '
                       'installed on your system') % gs_req)

    return flag


def _get_home():
    """Find user's home directory if possible.
    Otherwise raise error.

    :see:  http://mail.python.org/pipermail/python-list/2005-February/263921.html
    """
    path=''
    try:
        path=os.path.expanduser("~")
    except:
        pass
    if not os.path.isdir(path):
        for evar in ('HOME', 'USERPROFILE', 'TMP'):
            try:
                path = os.environ[evar]
                if os.path.isdir(path):
                    break
            except: pass
    if path:
        return path
    else:
        raise RuntimeError('please define environment variable $HOME')



get_home = verbose.wrap('$HOME=%s', _get_home, always=False)

def _get_configdir():
    """
    Return the string representing the configuration dir.

    default is HOME/.matplotlib.  you can override this with the
    MPLCONFIGDIR environment variable
    """

    configdir = os.environ.get('MPLCONFIGDIR')
    if configdir is not None:
        if not _is_writable_dir(configdir):
            raise RuntimeError('Could not write to MPLCONFIGDIR="%s"'%configdir)
        return configdir

    h = get_home()
    p = os.path.join(get_home(), '.matplotlib')

    if os.path.exists(p):
        if not _is_writable_dir(p):
            raise RuntimeError("'%s' is not a writable dir; you must set %s/.matplotlib to be a writable dir.  You can also set environment variable MPLCONFIGDIR to any writable directory where you want matplotlib data stored "% (h, h))
    else:
        if not _is_writable_dir(h):
            raise RuntimeError("Failed to create %s/.matplotlib; consider setting MPLCONFIGDIR to a writable directory for matplotlib configuration data"%h)

        os.mkdir(p)

    return p
get_configdir = verbose.wrap('CONFIGDIR=%s', _get_configdir, always=False)


def _get_data_path():
    'get the path to matplotlib data'

    if 'MATPLOTLIBDATA' in os.environ:
        path = os.environ['MATPLOTLIBDATA']
        if not os.path.isdir(path):
            raise RuntimeError('Path in environment MATPLOTLIBDATA not a directory')
        return path

    path = os.sep.join([os.path.dirname(__file__), 'mpl-data'])
    if os.path.isdir(path): return path

    # setuptools' namespace_packages may highjack this init file
    # so need to try something known to be in matplotlib, not basemap
    import matplotlib.afm
    path = os.sep.join([os.path.dirname(matplotlib.afm.__file__), 'mpl-data'])
    if os.path.isdir(path): return path

    # py2exe zips pure python, so still need special check
    if getattr(sys,'frozen',None):
        path = os.path.join(os.path.split(sys.path[0])[0], 'mpl-data')
        if os.path.isdir(path): return path
        else:
            # Try again assuming we need to step up one more directory
            path = os.path.join(os.path.split(os.path.split(sys.path[0])[0])[0],
                                'mpl-data')
        if os.path.isdir(path): return path
        else:
            # Try again assuming sys.path[0] is a dir not a exe
            path = os.path.join(sys.path[0], 'mpl-data')
            if os.path.isdir(path): return path

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

def _get_data_path_cached():
    if defaultParams['datapath'][0] is None:
        defaultParams['datapath'][0] = _get_data_path()
    return defaultParams['datapath'][0]

get_data_path = verbose.wrap('matplotlib data path %s', _get_data_path_cached,
                             always=False)


def get_example_data(fname):
    """
    return a filehandle to one of the example files in mpl-data/example

    *fname*
        the name of one of the files in mpl-data/example
    """
    datadir = os.path.join(get_data_path(), 'example')
    fullpath = os.path.join(datadir, fname)
    if not os.path.exists(fullpath):
        raise IOError('could not find matplotlib example file "%s" in data directory "%s"'%(
            fname, datadir))
    return file(fullpath, 'rb')


def get_py2exe_datafiles():
    datapath = get_data_path()
    head, tail = os.path.split(datapath)
    d = {}
    for root, dirs, files in os.walk(datapath):
        # Need to explicitly remove cocoa_agg files or py2exe complains
        # NOTE I dont know why, but do as previous version
        if 'Matplotlib.nib' in files:
            files.remove('Matplotlib.nib')
        files = [os.path.join(root, filename) for filename in files]
        root = root.replace(tail, 'mpl-data')
        root = root[root.index('mpl-data'):]
        d[root] = files
    return d.items()


def matplotlib_fname():
    """
    Return the path to the rc file

    Search order:

     * current working dir
     * environ var MATPLOTLIBRC
     * HOME/.matplotlib/matplotlibrc
     * MATPLOTLIBDATA/matplotlibrc


    """

    oldname = os.path.join( os.getcwd(), '.matplotlibrc')
    if os.path.exists(oldname):
        print >> sys.stderr, """\
WARNING: Old rc filename ".matplotlibrc" found in working dir
  and and renamed to new default rc file name "matplotlibrc"
  (no leading"dot"). """
        shutil.move('.matplotlibrc', 'matplotlibrc')

    home = get_home()
    oldname = os.path.join( home, '.matplotlibrc')
    if os.path.exists(oldname):
        configdir = get_configdir()
        newname = os.path.join(configdir, 'matplotlibrc')
        print >> sys.stderr, """\
WARNING: Old rc filename "%s" found and renamed to
  new default rc file name "%s"."""%(oldname, newname)

        shutil.move(oldname, newname)


    fname = os.path.join( os.getcwd(), 'matplotlibrc')
    if os.path.exists(fname): return fname

    if 'MATPLOTLIBRC' in os.environ:
        path =  os.environ['MATPLOTLIBRC']
        if os.path.exists(path):
            fname = os.path.join(path, 'matplotlibrc')
            if os.path.exists(fname):
                return fname

    fname = os.path.join(get_configdir(), 'matplotlibrc')
    if os.path.exists(fname): return fname


    path =  get_data_path() # guaranteed to exist or raise
    fname = os.path.join(path, 'matplotlibrc')
    if not os.path.exists(fname):
        warnings.warn('Could not find matplotlibrc; using defaults')
    return fname


_deprecated_map = {
    'text.fontstyle':   'font.style',
    'text.fontangle':   'font.style',
    'text.fontvariant': 'font.variant',
    'text.fontweight':  'font.weight',
    'text.fontsize':    'font.size',
    'tick.size' :       'tick.major.size',
    }

_deprecated_ignore_map = {
    'legend.pad' :       'legend.borderpad',
    'legend.labelsep' :       'legend.labelspacing',
    'legend.handlelen' :       'legend.handlelength',
    'legend.handletextsep' :       'legend.handletextpad',
    'legend.axespad' :       'legend.borderaxespad',
    }


class RcParams(dict):

    """
    A dictionary object including validation

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

    validate = dict([ (key, converter) for key, (default, converter) in \
                     defaultParams.iteritems() ])

    def __setitem__(self, key, val):
        try:
            if key in _deprecated_map.keys():
                alt = _deprecated_map[key]
                warnings.warn('%s is deprecated in matplotlibrc. Use %s \
instead.'% (key, alt))
                key = alt
            elif key in _deprecated_ignore_map:
                alt = _deprecated_ignore_map[key]
                warnings.warn('%s is deprecated. Use %s instead.'% (key, alt))
                return
            cval = self.validate[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)


def rc_params(fail_on_error=False):
    'Return the default params updated from the values in the rc file'

    fname = matplotlib_fname()
    if not os.path.exists(fname):
        # this should never happen, default in mpl-data should always be found
        message = 'could not find rc file; returning defaults'
        ret = RcParams([ (key, default) for key, (default, converter) in \
                        defaultParams.iteritems() ])
        warnings.warn(message)
        return ret

    cnt = 0
    rc_temp = {}
    for line in file(fname):
        cnt += 1
        strippedline = line.split('#',1)[0].strip()
        if not strippedline: continue
        tup = strippedline.split(':',1)
        if len(tup) !=2:
            warnings.warn('Illegal line #%d\n\t%s\n\tin file "%s"'%\
                          (cnt, line, fname))
            continue
        key, val = tup
        key = key.strip()
        val = val.strip()
        if key in rc_temp:
            warnings.warn('Duplicate key in file "%s", line #%d'%(fname,cnt))
        rc_temp[key] = (val, line, cnt)

    ret = RcParams([ (key, default) for key, (default, converter) in \
                    defaultParams.iteritems() ])

    for key in ('verbose.level', 'verbose.fileo'):
        if key in rc_temp:
            val, line, cnt = rc_temp.pop(key)
            if fail_on_error:
                ret[key] = val # try to convert to proper type or raise
            else:
                try: ret[key] = val # try to convert to proper type or skip
                except Exception, msg:
                    warnings.warn('Bad val "%s" on line #%d\n\t"%s"\n\tin file \
"%s"\n\t%s' % (val, cnt, line, fname, msg))

    verbose.set_level(ret['verbose.level'])
    verbose.set_fileo(ret['verbose.fileo'])

    for key, (val, line, cnt) in rc_temp.iteritems():
        if key in defaultParams:
            if fail_on_error:
                ret[key] = val # try to convert to proper type or raise
            else:
                try: ret[key] = val # try to convert to proper type or skip
                except Exception, msg:
                    warnings.warn('Bad val "%s" on line #%d\n\t"%s"\n\tin file \
"%s"\n\t%s' % (val, cnt, line, fname, msg))
        elif key in _deprecated_ignore_map:
            warnings.warn('%s is deprecated. Update your matplotlibrc to use %s instead.'% (key, _deprecated_ignore_map[key]))

        else:
            print >> sys.stderr, """
Bad key "%s" on line %d in
%s.
You probably need to get an updated matplotlibrc file from
http://matplotlib.sf.net/_static/matplotlibrc or from the matplotlib source
distribution""" % (key, cnt, fname)

    if ret['datapath'] is None:
        ret['datapath'] = get_data_path()

    if not ret['text.latex.preamble'] == ['']:
        verbose.report("""
*****************************************************************
You have the following UNSUPPORTED LaTeX preamble customizations:
%s
Please do not ask for support with these customizations active.
*****************************************************************
"""% '\n'.join(ret['text.latex.preamble']), 'helpful')

    verbose.report('loaded rc file %s'%fname)

    return ret


# this is the instance used by the matplotlib classes
rcParams = rc_params()

rcParamsDefault = RcParams([ (key, default) for key, (default, converter) in \
                    defaultParams.iteritems() ])

rcParams['ps.usedistiller'] = checkdep_ps_distiller(rcParams['ps.usedistiller'])
rcParams['text.usetex'] = checkdep_usetex(rcParams['text.usetex'])

def rc(group, **kwargs):
    """
    Set the current rc params.  Group is the grouping for the rc, eg.
    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, eg. (*xtick*, *ytick*).
    *kwargs* is a dictionary attribute name/value pairs, eg::

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

    sets the current rc params 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 rc command as::

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


    Note you can use python's kwargs dictionary facility to store
    dictionaries of default parameters.  Eg, 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 :func:`~matplotlib.pyplot.rcdefaults` to restore the default
    rc params after changes.
    """

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

    if is_string_like(group):
        group = (group,)
    for g in group:
        for k,v in kwargs.items():
            name = aliases.get(k) or k
            key = '%s.%s' % (g, name)
            if key not in rcParams:
                raise KeyError('Unrecognized key "%s" for group "%s" and name "%s"' %
                               (key, g, name))

            rcParams[key] = v

def rcdefaults():
    """
    Restore the default rc params - the ones that were created at
    matplotlib load time.
    """
    rcParams.update(rcParamsDefault)

if NEWCONFIG:
    #print "importing from reorganized config system!"
    try:
        from config import rcParams, rcdefaults, mplConfig, save_config
        verbose.set_level(rcParams['verbose.level'])
        verbose.set_fileo(rcParams['verbose.fileo'])
    except:
        from config import rcParams, rcdefaults

_use_error_msg = """ This call to matplotlib.use() has no effect
because the the backend has already been chosen;
matplotlib.use() must be called *before* pylab, matplotlib.pyplot,
or matplotlib.backends is imported for the first time.
"""

def use(arg, warn=True):
    """
    Set the matplotlib backend to one of the known backends.

    The argument is case-insensitive.  For the Cairo backend,
    the argument can have an extension to indicate the type of
    output.  Example:

        use('cairo.pdf')

    will specify a default of pdf output generated by Cairo.

    Note: this function must be called *before* importing pylab for
    the first time; or, if you are not using pylab, it must be called
    before importing matplotlib.backends.  If warn is True, a warning
    is issued if you try and callthis after pylab or pyplot have been
    loaded.  In certain black magic use cases, eg
    pyplot.switch_backends, we are doing the reloading necessary to
    make the backend switch work (in some cases, eg pure image
    backends) so one can set warn=False to supporess the warnings
    """
    if 'matplotlib.backends' in sys.modules:
        if warn: warnings.warn(_use_error_msg)
        return
    arg = arg.lower()
    if arg.startswith('module://'):
        name = arg
    else:
        be_parts = arg.split('.')
        name = validate_backend(be_parts[0])
        if len(be_parts) > 1:
            if name == 'cairo':
                rcParams['cairo.format'] = validate_cairo_format(be_parts[1])
            else:
                raise ValueError('Only cairo backend has a format option')
    rcParams['backend'] = name

def get_backend():
    "Returns the current backend"
    return rcParams['backend']

def interactive(b):
    """
    Set interactive mode to boolean b.

    If b is True, then draw after every plotting command, eg, after xlabel
    """
    rcParams['interactive'] = b

def is_interactive():
    'Return true if plot mode is interactive'
    b = rcParams['interactive']
    return b

def tk_window_focus():
    """Return true if focus maintenance under TkAgg on win32 is on.
     This currently works only for python.exe and IPython.exe.
     Both IDLE and Pythonwin.exe fail badly when tk_window_focus is on."""
    if rcParams['backend'] != 'TkAgg':
        return False
    return rcParams['tk.window_focus']

# Now allow command line to override

# Allow command line access to the backend with -d (matlab compatible
# flag)

for s in sys.argv[1:]:
    if s.startswith('-d') and len(s) > 2:  # look for a -d flag
        try:
            use(s[2:])
        except (KeyError, ValueError):
            pass
        # we don't want to assume all -d flags are backends, eg -debug


verbose.report('matplotlib version %s'%__version__)
verbose.report('verbose.level %s'%verbose.level)
verbose.report('interactive is %s'%rcParams['interactive'])
verbose.report('units is %s'%rcParams['units'])
verbose.report('platform is %s'%sys.platform)
verbose.report('loaded modules: %s'%sys.modules.keys(), 'debug')
