"""
The figure module provides the top-level
:class:`~matplotlib.artist.Artist`, the :class:`Figure`, which
contains all the plot elements.  The following classes are defined

:class:`SubplotParams`
    control the default spacing of the subplots

:class:`Figure`
    top level container for all plot elements

"""

from __future__ import (absolute_import, division, print_function,
                        unicode_literals)

import six

import warnings

import numpy as np

from matplotlib import rcParams
from matplotlib import docstring
from matplotlib import __version__ as _mpl_version

import matplotlib.artist as martist
from matplotlib.artist import Artist, allow_rasterization

import matplotlib.cbook as cbook

from matplotlib.cbook import Stack, iterable

from matplotlib import image as mimage
from matplotlib.image import FigureImage

import matplotlib.colorbar as cbar

from matplotlib.axes import Axes, SubplotBase, subplot_class_factory
from matplotlib.blocking_input import BlockingMouseInput, BlockingKeyMouseInput
from matplotlib.gridspec import GridSpec
import matplotlib.legend as mlegend
from matplotlib.patches import Rectangle
from matplotlib.projections import (get_projection_names,
                                    process_projection_requirements)
from matplotlib.text import Text, _process_text_args
from matplotlib.transforms import (Affine2D, Bbox, BboxTransformTo,
                                   TransformedBbox)
from matplotlib.backend_bases import NonGuiException

docstring.interpd.update(projection_names=get_projection_names())


def _stale_figure_callback(self, val):
    if self.figure:
        self.figure.stale = val


class AxesStack(Stack):
    """
    Specialization of the Stack to handle all tracking of Axes in a Figure.
    This stack stores ``key, (ind, axes)`` pairs, where:

        * **key** should be a hash of the args and kwargs
          used in generating the Axes.
        * **ind** is a serial number for tracking the order
          in which axes were added.

    The AxesStack is a callable, where ``ax_stack()`` returns
    the current axes. Alternatively the :meth:`current_key_axes` will
    return the current key and associated axes.

    """
    def __init__(self):
        Stack.__init__(self)
        self._ind = 0

    def as_list(self):
        """
        Return a list of the Axes instances that have been added to the figure
        """
        ia_list = [a for k, a in self._elements]
        ia_list.sort()
        return [a for i, a in ia_list]

    def get(self, key):
        """
        Return the Axes instance that was added with *key*.
        If it is not present, return None.
        """
        item = dict(self._elements).get(key)
        if item is None:
            return None
        cbook.warn_deprecated(
            "2.1",
            "Adding an axes using the same arguments as a previous axes "
            "currently reuses the earlier instance.  In a future version, "
            "a new instance will always be created and returned.  Meanwhile, "
            "this warning can be suppressed, and the future behavior ensured, "
            "by passing a unique label to each axes instance.")
        return item[1]

    def _entry_from_axes(self, e):
        ind, k = {a: (ind, k) for k, (ind, a) in self._elements}[e]
        return (k, (ind, e))

    def remove(self, a):
        """Remove the axes from the stack."""
        Stack.remove(self, self._entry_from_axes(a))

    def bubble(self, a):
        """
        Move the given axes, which must already exist in the
        stack, to the top.
        """
        return Stack.bubble(self, self._entry_from_axes(a))

    def add(self, key, a):
        """
        Add Axes *a*, with key *key*, to the stack, and return the stack.

        If *key* is unhashable, replace it by a unique, arbitrary object.

        If *a* is already on the stack, don't add it again, but
        return *None*.
        """
        # All the error checking may be unnecessary; but this method
        # is called so seldom that the overhead is negligible.
        if not isinstance(a, Axes):
            raise ValueError("second argument, {!r}, is not an Axes".format(a))
        try:
            hash(key)
        except TypeError:
            key = object()

        a_existing = self.get(key)
        if a_existing is not None:
            Stack.remove(self, (key, a_existing))
            warnings.warn(
                "key {!r} already existed; Axes is being replaced".format(key))
            # I don't think the above should ever happen.

        if a in self:
            return None
        self._ind += 1
        return Stack.push(self, (key, (self._ind, a)))

    def current_key_axes(self):
        """
        Return a tuple of ``(key, axes)`` for the active axes.

        If no axes exists on the stack, then returns ``(None, None)``.

        """
        if not len(self._elements):
            return self._default, self._default
        else:
            key, (index, axes) = self._elements[self._pos]
            return key, axes

    def __call__(self):
        return self.current_key_axes()[1]

    def __contains__(self, a):
        return a in self.as_list()


class SubplotParams(object):
    """
    A class to hold the parameters for a subplot
    """
    def __init__(self, left=None, bottom=None, right=None, top=None,
                 wspace=None, hspace=None):
        """
        All dimensions are fraction of the figure width or height.
        All values default to their rc params

        The following attributes are available

        left  : 0.125
            The left side of the subplots of the figure

        right : 0.9
            The right side of the subplots of the figure

        bottom : 0.1
            The bottom of the subplots of the figure

        top : 0.9
            The top of the subplots of the figure

        wspace : 0.2
            The amount of width reserved for blank space between subplots,
            expressed as a fraction of the average axis width

        hspace : 0.2
            The amount of height reserved for white space between subplots,
            expressed as a fraction of the average axis height
        """

        self.validate = True
        self.update(left, bottom, right, top, wspace, hspace)

    def update(self, left=None, bottom=None, right=None, top=None,
               wspace=None, hspace=None):
        """
        Update the current values.  If any kwarg is None, default to
        the current value, if set, otherwise to rc

        """

        thisleft = getattr(self, 'left', None)
        thisright = getattr(self, 'right', None)
        thistop = getattr(self, 'top', None)
        thisbottom = getattr(self, 'bottom', None)
        thiswspace = getattr(self, 'wspace', None)
        thishspace = getattr(self, 'hspace', None)

        self._update_this('left', left)
        self._update_this('right', right)
        self._update_this('bottom', bottom)
        self._update_this('top', top)
        self._update_this('wspace', wspace)
        self._update_this('hspace', hspace)

        def reset():
            self.left = thisleft
            self.right = thisright
            self.top = thistop
            self.bottom = thisbottom
            self.wspace = thiswspace
            self.hspace = thishspace

        if self.validate:
            if self.left >= self.right:
                reset()
                raise ValueError('left cannot be >= right')

            if self.bottom >= self.top:
                reset()
                raise ValueError('bottom cannot be >= top')

    def _update_this(self, s, val):
        if val is None:
            val = getattr(self, s, None)
            if val is None:
                key = 'figure.subplot.' + s
                val = rcParams[key]

        setattr(self, s, val)


class Figure(Artist):

    """
    The Figure instance supports callbacks through a *callbacks*
    attribute which is a :class:`matplotlib.cbook.CallbackRegistry`
    instance.  The events you can connect to are 'dpi_changed', and
    the callback will be called with ``func(fig)`` where fig is the
    :class:`Figure` instance.

    *patch*
       The figure patch is drawn by a
       :class:`matplotlib.patches.Rectangle` instance

    *suppressComposite*
       For multiple figure images, the figure will make composite
       images depending on the renderer option_image_nocomposite
       function.  If suppressComposite is True|False, this will
       override the renderer.
    """

    def __str__(self):
        return "Figure(%gx%g)" % tuple(self.bbox.size)

    def __init__(self,
                 figsize=None,  # defaults to rc figure.figsize
                 dpi=None,  # defaults to rc figure.dpi
                 facecolor=None,  # defaults to rc figure.facecolor
                 edgecolor=None,  # defaults to rc figure.edgecolor
                 linewidth=0.0,  # the default linewidth of the frame
                 frameon=None,  # whether or not to draw the figure frame
                 subplotpars=None,  # default to rc
                 tight_layout=None,  # default to rc figure.autolayout
                 ):
        """
        *figsize*
            w,h tuple in inches

        *dpi*
            Dots per inch

        *facecolor*
            The figure patch facecolor; defaults to rc ``figure.facecolor``

        *edgecolor*
            The figure patch edge color; defaults to rc ``figure.edgecolor``

        *linewidth*
            The figure patch edge linewidth; the default linewidth of the frame

        *frameon*
            If *False*, suppress drawing the figure frame

        *subplotpars*
            A :class:`SubplotParams` instance, defaults to rc

        *tight_layout*
            If *False* use *subplotpars*; if *True* adjust subplot
            parameters using :meth:`tight_layout` with default padding.
            When providing a dict containing the keys `pad`, `w_pad`, `h_pad`
            and `rect`, the default :meth:`tight_layout` paddings will be
            overridden.
            Defaults to rc ``figure.autolayout``.
        """
        Artist.__init__(self)
        # remove the non-figure artist _axes property
        # as it makes no sense for a figure to be _in_ an axes
        # this is used by the property methods in the artist base class
        # which are over-ridden in this class
        del self._axes
        self.callbacks = cbook.CallbackRegistry()

        if figsize is None:
            figsize = rcParams['figure.figsize']
        if dpi is None:
            dpi = rcParams['figure.dpi']
        if facecolor is None:
            facecolor = rcParams['figure.facecolor']
        if edgecolor is None:
            edgecolor = rcParams['figure.edgecolor']
        if frameon is None:
            frameon = rcParams['figure.frameon']

        if not np.isfinite(figsize).all():
            raise ValueError('figure size must be finite not '
                             '{}'.format(figsize))
        self.bbox_inches = Bbox.from_bounds(0, 0, *figsize)

        self.dpi_scale_trans = Affine2D().scale(dpi, dpi)
        # do not use property as it will trigger
        self._dpi = dpi
        self.bbox = TransformedBbox(self.bbox_inches, self.dpi_scale_trans)

        self.frameon = frameon

        self.transFigure = BboxTransformTo(self.bbox)

        self.patch = Rectangle(
            xy=(0, 0), width=1, height=1,
            facecolor=facecolor, edgecolor=edgecolor, linewidth=linewidth)
        self._set_artist_props(self.patch)
        self.patch.set_aa(False)

        self._hold = rcParams['axes.hold']
        if self._hold is None:
            self._hold = True

        self.canvas = None
        self._suptitle = None

        if subplotpars is None:
            subplotpars = SubplotParams()

        self.subplotpars = subplotpars
        self.set_tight_layout(tight_layout)

        self._axstack = AxesStack()  # track all figure axes and current axes
        self.clf()
        self._cachedRenderer = None

    @property
    @cbook.deprecated("2.1", alternative="Figure.patch")
    def figurePatch(self):
        return self.patch

    # TODO: I'd like to dynamically add the _repr_html_ method
    # to the figure in the right context, but then IPython doesn't
    # use it, for some reason.

    def _repr_html_(self):
        # We can't use "isinstance" here, because then we'd end up importing
        # webagg unconditiionally.
        if (self.canvas is not None and
            'WebAgg' in self.canvas.__class__.__name__):
            from matplotlib.backends import backend_webagg
            return backend_webagg.ipython_inline_display(self)

    def show(self, warn=True):
        """
        If using a GUI backend with pyplot, display the figure window.

        If the figure was not created using
        :func:`~matplotlib.pyplot.figure`, it will lack a
        :class:`~matplotlib.backend_bases.FigureManagerBase`, and
        will raise an AttributeError.

        For non-GUI backends, this does nothing, in which case
        a warning will be issued if *warn* is True (default).
        """
        try:
            manager = getattr(self.canvas, 'manager')
        except AttributeError as err:
            raise AttributeError("%s\n"
                                 "Figure.show works only "
                                 "for figures managed by pyplot, normally "
                                 "created by pyplot.figure()." % err)

        if manager is not None:
            try:
                manager.show()
                return
            except NonGuiException:
                pass
        if warn:
            import warnings
            warnings.warn(
                "matplotlib is currently using a non-GUI backend, "
                "so cannot show the figure")

    def _get_axes(self):
        return self._axstack.as_list()

    axes = property(fget=_get_axes, doc="Read-only: list of axes in Figure")

    def _get_dpi(self):
        return self._dpi

    def _set_dpi(self, dpi, forward=True):
        """
        The forward kwarg is passed on to set_size_inches
        """
        self._dpi = dpi
        self.dpi_scale_trans.clear().scale(dpi, dpi)
        w, h = self.get_size_inches()
        self.set_size_inches(w, h, forward=forward)
        self.callbacks.process('dpi_changed', self)

    dpi = property(_get_dpi, _set_dpi)

    def get_tight_layout(self):
        """
        Return the Boolean flag, True to use :meth:`tight_layout` when drawing.
        """
        return self._tight

    def set_tight_layout(self, tight):
        """
        Set whether :meth:`tight_layout` is used upon drawing.
        If None, the rcParams['figure.autolayout'] value will be set.

        When providing a dict containing the keys `pad`, `w_pad`, `h_pad`
        and `rect`, the default :meth:`tight_layout` paddings will be
        overridden.

        ACCEPTS: [True | False | dict | None ]
        """
        if tight is None:
            tight = rcParams['figure.autolayout']
        self._tight = bool(tight)
        self._tight_parameters = tight if isinstance(tight, dict) else {}
        self.stale = True

    def autofmt_xdate(self, bottom=0.2, rotation=30, ha='right', which=None):
        """
        Date ticklabels often overlap, so it is useful to rotate them
        and right align them.  Also, a common use case is a number of
        subplots with shared xaxes where the x-axis is date data.  The
        ticklabels are often long, and it helps to rotate them on the
        bottom subplot and turn them off on other subplots, as well as
        turn off xlabels.

        Parameters
        ----------

        bottom : scalar
            The bottom of the subplots for :meth:`subplots_adjust`

        rotation : angle in degrees
            The rotation of the xtick labels

        ha : string
            The horizontal alignment of the xticklabels

        which : {None, 'major', 'minor', 'both'}
            Selects which ticklabels to rotate (default is None which works
            same as major)
        """
        allsubplots = all(hasattr(ax, 'is_last_row') for ax in self.axes)
        if len(self.axes) == 1:
            for label in self.axes[0].get_xticklabels(which=which):
                label.set_ha(ha)
                label.set_rotation(rotation)
        else:
            if allsubplots:
                for ax in self.get_axes():
                    if ax.is_last_row():
                        for label in ax.get_xticklabels(which=which):
                            label.set_ha(ha)
                            label.set_rotation(rotation)
                    else:
                        for label in ax.get_xticklabels(which=which):
                            label.set_visible(False)
                        ax.set_xlabel('')

        if allsubplots:
            self.subplots_adjust(bottom=bottom)
        self.stale = True

    def get_children(self):
        'get a list of artists contained in the figure'
        children = [self.patch]
        children.extend(self.artists)
        children.extend(self.axes)
        children.extend(self.lines)
        children.extend(self.patches)
        children.extend(self.texts)
        children.extend(self.images)
        children.extend(self.legends)
        return children

    def contains(self, mouseevent):
        """
        Test whether the mouse event occurred on the figure.

        Returns True, {}.
        """
        if callable(self._contains):
            return self._contains(self, mouseevent)
        inside = self.bbox.contains(mouseevent.x, mouseevent.y)
        return inside, {}

    def get_window_extent(self, *args, **kwargs):
        'get the figure bounding box in display space; kwargs are void'
        return self.bbox

    def suptitle(self, t, **kwargs):
        """
        Add a centered title to the figure.

        kwargs are :class:`matplotlib.text.Text` properties.  Using figure
        coordinates, the defaults are:

          x : 0.5
            The x location of the text in figure coords

          y : 0.98
            The y location of the text in figure coords

          horizontalalignment : 'center'
            The horizontal alignment of the text

          verticalalignment : 'top'
            The vertical alignment of the text

        If the `fontproperties` keyword argument is given then the
        rcParams defaults for `fontsize` (`figure.titlesize`) and
        `fontweight` (`figure.titleweight`) will be ignored in favour
        of the `FontProperties` defaults.

        A :class:`matplotlib.text.Text` instance is returned.

        Example::

          fig.suptitle('this is the figure title', fontsize=12)
        """
        x = kwargs.pop('x', 0.5)
        y = kwargs.pop('y', 0.98)

        if ('horizontalalignment' not in kwargs) and ('ha' not in kwargs):
            kwargs['horizontalalignment'] = 'center'
        if ('verticalalignment' not in kwargs) and ('va' not in kwargs):
            kwargs['verticalalignment'] = 'top'

        if 'fontproperties' not in kwargs:
            if 'fontsize' not in kwargs and 'size' not in kwargs:
                kwargs['size'] = rcParams['figure.titlesize']
            if 'fontweight' not in kwargs and 'weight' not in kwargs:
                kwargs['weight'] = rcParams['figure.titleweight']

        sup = self.text(x, y, t, **kwargs)
        if self._suptitle is not None:
            self._suptitle.set_text(t)
            self._suptitle.set_position((x, y))
            self._suptitle.update_from(sup)
            sup.remove()
        else:
            self._suptitle = sup

        self.stale = True
        return self._suptitle

    def set_canvas(self, canvas):
        """
        Set the canvas that contains the figure

        ACCEPTS: a FigureCanvas instance
        """
        self.canvas = canvas

    @cbook.deprecated("2.0")
    def hold(self, b=None):
        """
        Set the hold state.  If hold is None (default), toggle the
        hold state.  Else set the hold state to boolean value b.

        e.g.::

            hold()      # toggle hold
            hold(True)  # hold is on
            hold(False) # hold is off

        All "hold" machinery is deprecated.
        """
        if b is None:
            self._hold = not self._hold
        else:
            self._hold = b

    def figimage(self, X,
                 xo=0,
                 yo=0,
                 alpha=None,
                 norm=None,
                 cmap=None,
                 vmin=None,
                 vmax=None,
                 origin=None,
                 resize=False,
                 **kwargs):
        """
        Adds a non-resampled image to the figure.

        call signatures::

          figimage(X, **kwargs)

        adds a non-resampled array *X* to the figure.

        ::

          figimage(X, xo, yo)

        with pixel offsets *xo*, *yo*,

        *X* must be a float array:

        * If *X* is MxN, assume luminance (grayscale)
        * If *X* is MxNx3, assume RGB
        * If *X* is MxNx4, assume RGBA

        Optional keyword arguments:

          =========   =========================================================
          Keyword     Description
          =========   =========================================================
          resize      a boolean, True or False. If "True", then re-size the
                      Figure to match the given image size.
          xo or yo    An integer, the *x* and *y* image offset in pixels
          cmap        a :class:`matplotlib.colors.Colormap` instance, e.g.,
                      cm.jet. If *None*, default to the rc ``image.cmap``
                      value
          norm        a :class:`matplotlib.colors.Normalize` instance. The
                      default is normalization().  This scales luminance -> 0-1
          vmin|vmax   are used to scale a luminance image to 0-1.  If either
                      is *None*, the min and max of the luminance values will
                      be used.  Note if you pass a norm instance, the settings
                      for *vmin* and *vmax* will be ignored.
          alpha       the alpha blending value, default is *None*
          origin      [ 'upper' | 'lower' ] Indicates where the [0,0] index of
                      the array is in the upper left or lower left corner of
                      the axes. Defaults to the rc image.origin value
          =========   =========================================================

        figimage complements the axes image
        (:meth:`~matplotlib.axes.Axes.imshow`) which will be resampled
        to fit the current axes.  If you want a resampled image to
        fill the entire figure, you can define an
        :class:`~matplotlib.axes.Axes` with extent [0,0,1,1].

        An :class:`matplotlib.image.FigureImage` instance is returned.

        Additional kwargs are Artist kwargs passed on to
        :class:`~matplotlib.image.FigureImage`
        """

        if not self._hold:
            self.clf()

        if resize:
            dpi = self.get_dpi()
            figsize = [x / float(dpi) for x in (X.shape[1], X.shape[0])]
            self.set_size_inches(figsize, forward=True)

        im = FigureImage(self, cmap, norm, xo, yo, origin, **kwargs)
        im.stale_callback = _stale_figure_callback

        im.set_array(X)
        im.set_alpha(alpha)
        if norm is None:
            im.set_clim(vmin, vmax)
        self.images.append(im)
        im._remove_method = lambda h: self.images.remove(h)
        self.stale = True
        return im

    def set_size_inches(self, w, h=None, forward=True):
        """Set the figure size in inches (1in == 2.54cm)

        Usage ::

             fig.set_size_inches(w, h)  # OR
             fig.set_size_inches((w, h))

        optional kwarg *forward=True* will cause the canvas size to be
        automatically updated; e.g., you can resize the figure window
        from the shell

        ACCEPTS: a w, h tuple with w, h in inches

        See Also
        --------

        matplotlib.Figure.get_size_inches
        """

        # the width and height have been passed in as a tuple to the first
        # argument, so unpack them
        if h is None:
            w, h = w
        if not all(np.isfinite(_) for _ in (w, h)):
            raise ValueError('figure size must be finite not '
                             '({}, {})'.format(w, h))
        self.bbox_inches.p1 = w, h

        if forward:
            canvas = getattr(self, 'canvas')
            if canvas is not None:
                ratio = getattr(self.canvas, '_dpi_ratio', 1)
                dpival = self.dpi / ratio
                canvasw = w * dpival
                canvash = h * dpival
                manager = getattr(self.canvas, 'manager', None)
                if manager is not None:
                    manager.resize(int(canvasw), int(canvash))
        self.stale = True

    def get_size_inches(self):
        """
        Returns the current size of the figure in inches (1in == 2.54cm)
        as an numpy array.

        Returns
        -------
        size : ndarray
           The size of the figure in inches

        See Also
        --------

        matplotlib.Figure.set_size_inches
        """
        return np.array(self.bbox_inches.p1)

    def get_edgecolor(self):
        'Get the edge color of the Figure rectangle'
        return self.patch.get_edgecolor()

    def get_facecolor(self):
        'Get the face color of the Figure rectangle'
        return self.patch.get_facecolor()

    def get_figwidth(self):
        'Return the figwidth as a float'
        return self.bbox_inches.width

    def get_figheight(self):
        'Return the figheight as a float'
        return self.bbox_inches.height

    def get_dpi(self):
        'Return the dpi as a float'
        return self.dpi

    def get_frameon(self):
        'get the boolean indicating frameon'
        return self.frameon

    def set_edgecolor(self, color):
        """
        Set the edge color of the Figure rectangle

        ACCEPTS: any matplotlib color - see help(colors)
        """
        self.patch.set_edgecolor(color)

    def set_facecolor(self, color):
        """
        Set the face color of the Figure rectangle

        ACCEPTS: any matplotlib color - see help(colors)
        """
        self.patch.set_facecolor(color)

    def set_dpi(self, val):
        """
        Set the dots-per-inch of the figure

        ACCEPTS: float
        """
        self.dpi = val
        self.stale = True

    def set_figwidth(self, val, forward=False):
        """
        Set the width of the figure in inches

        ACCEPTS: float
        """
        self.set_size_inches(val, self.get_figheight(), forward=forward)

    def set_figheight(self, val, forward=False):
        """
        Set the height of the figure in inches

        ACCEPTS: float
        """
        self.set_size_inches(self.get_figwidth(), val, forward=forward)

    def set_frameon(self, b):
        """
        Set whether the figure frame (background) is displayed or invisible

        ACCEPTS: boolean
        """
        self.frameon = b
        self.stale = True

    def delaxes(self, a):
        'remove a from the figure and update the current axes'
        self._axstack.remove(a)
        for func in self._axobservers:
            func(self)
        self.stale = True

    def _make_key(self, *args, **kwargs):
        'make a hashable key out of args and kwargs'

        def fixitems(items):
            #items may have arrays and lists in them, so convert them
            # to tuples for the key
            ret = []
            for k, v in items:
                # some objects can define __getitem__ without being
                # iterable and in those cases the conversion to tuples
                # will fail. So instead of using the iterable(v) function
                # we simply try and convert to a tuple, and proceed if not.
                try:
                    v = tuple(v)
                except Exception:
                    pass
                ret.append((k, v))
            return tuple(ret)

        def fixlist(args):
            ret = []
            for a in args:
                if iterable(a):
                    a = tuple(a)
                ret.append(a)
            return tuple(ret)

        key = fixlist(args), fixitems(six.iteritems(kwargs))
        return key

    def add_axes(self, *args, **kwargs):
        """
        Add an axes at position *rect* [*left*, *bottom*, *width*,
        *height*] where all quantities are in fractions of figure
        width and height.

        Parameters
        ----------
        rect : sequence of float
            A 4-length sequence of [left, bottom, width, height] quantities.

        projection :
            ['aitoff' | 'hammer' | 'lambert' | 'mollweide' | \
'polar' | 'rectilinear'], optional
            The projection type of the axes.

        polar : boolean, optional
            If True, equivalent to projection='polar'.

        **kwargs
            This method also takes the keyword arguments for
            :class:`~matplotlib.axes.Axes`.

        Returns
        -------
        axes : Axes
            The added axes.

        Examples
        --------
        A simple example::

            rect = l,b,w,h
            fig.add_axes(rect)
            fig.add_axes(rect, frameon=False, facecolor='g')
            fig.add_axes(rect, polar=True)
            fig.add_axes(rect, projection='polar')
            fig.add_axes(ax)

        If the figure already has an axes with the same parameters, then it
        will simply make that axes current and return it.  This behavior
        has been deprecated as of Matplotlib 2.1.  Meanwhile, if you do
        not want this behavior (i.e., you want to force the creation of a
        new Axes), you must use a unique set of args and kwargs.  The axes
        :attr:`~matplotlib.axes.Axes.label` attribute has been exposed for this
        purpose: if you want two axes that are otherwise identical to be added
        to the figure, make sure you give them unique labels::

            fig.add_axes(rect, label='axes1')
            fig.add_axes(rect, label='axes2')

        In rare circumstances, add_axes may be called with a single
        argument, an Axes instance already created in the present
        figure but not in the figure's list of axes.  For example,
        if an axes has been removed with :meth:`delaxes`, it can
        be restored with::

            fig.add_axes(ax)

        In all cases, the :class:`~matplotlib.axes.Axes` instance
        will be returned.
        """
        if not len(args):
            return

        # shortcut the projection "key" modifications later on, if an axes
        # with the exact args/kwargs exists, return it immediately.
        key = self._make_key(*args, **kwargs)
        ax = self._axstack.get(key)
        if ax is not None:
            self.sca(ax)
            return ax

        if isinstance(args[0], Axes):
            a = args[0]
            if a.get_figure() is not self:
                msg = "The Axes must have been created in the present figure"
                raise ValueError(msg)
        else:
            rect = args[0]
            if not np.isfinite(rect).all():
                raise ValueError('all entries in rect must be finite '
                                 'not {}'.format(rect))
            projection_class, kwargs, key = process_projection_requirements(
                self, *args, **kwargs)

            # check that an axes of this type doesn't already exist, if it
            # does, set it as active and return it
            ax = self._axstack.get(key)
            if isinstance(ax, projection_class):
                self.sca(ax)
                return ax

            # create the new axes using the axes class given
            a = projection_class(self, rect, **kwargs)

        self._axstack.add(key, a)
        self.sca(a)
        a._remove_method = self.__remove_ax
        self.stale = True
        a.stale_callback = _stale_figure_callback
        return a

    def add_subplot(self, *args, **kwargs):
        """
        Add a subplot.

        Parameters
        ----------
        *args
            Either a 3-digit integer or three separate integers
            describing the position of the subplot. If the three
            integers are I, J, and K, the subplot is the Ith plot on a
            grid with J rows and K columns.

        projection : ['aitoff' | 'hammer' | 'lambert' | \
'mollweide' | 'polar' | 'rectilinear'], optional
            The projection type of the axes.

        polar : boolean, optional
            If True, equivalent to projection='polar'.

        **kwargs
            This method also takes the keyword arguments for
            :class:`~matplotlib.axes.Axes`.

        Returns
        -------
        axes : Axes
            The axes of the subplot.

        Notes
        -----
        If the figure already has a subplot with key (*args*,
        *kwargs*) then it will simply make that subplot current and
        return it.  This behavior is deprecated.

        Examples
        --------
        ::

            fig.add_subplot(111)

            # equivalent but more general
            fig.add_subplot(1, 1, 1)

            # add subplot with red background
            fig.add_subplot(212, facecolor='r')

            # add a polar subplot
            fig.add_subplot(111, projection='polar')

            # add Subplot instance sub
            fig.add_subplot(sub)

        See Also
        --------
        matplotlib.pyplot.subplot : for an explanation of the args.
        """
        if not len(args):
            return

        if len(args) == 1 and isinstance(args[0], int):
            if not 100 <= args[0] <= 999:
                raise ValueError("Integer subplot specification must be a "
                                 "three-digit number, not {}".format(args[0]))
            args = tuple(map(int, str(args[0])))

        if isinstance(args[0], SubplotBase):

            a = args[0]
            if a.get_figure() is not self:
                msg = ("The Subplot must have been created in the present "
                       "figure")
                raise ValueError(msg)
            # make a key for the subplot (which includes the axes object id
            # in the hash)
            key = self._make_key(*args, **kwargs)
        else:
            projection_class, kwargs, key = process_projection_requirements(
                self, *args, **kwargs)

            # try to find the axes with this key in the stack
            ax = self._axstack.get(key)

            if ax is not None:
                if isinstance(ax, projection_class):
                    # the axes already existed, so set it as active & return
                    self.sca(ax)
                    return ax
                else:
                    # Undocumented convenience behavior:
                    # subplot(111); subplot(111, projection='polar')
                    # will replace the first with the second.
                    # Without this, add_subplot would be simpler and
                    # more similar to add_axes.
                    self._axstack.remove(ax)

            a = subplot_class_factory(projection_class)(self, *args, **kwargs)

        self._axstack.add(key, a)
        self.sca(a)
        a._remove_method = self.__remove_ax
        self.stale = True
        a.stale_callback = _stale_figure_callback
        return a

    def subplots(self, nrows=1, ncols=1, sharex=False, sharey=False,
                 squeeze=True, subplot_kw=None, gridspec_kw=None):
        """
        Add a set of subplots to this figure.

        Parameters
        ----------
        nrows, ncols : int, default: 1
            Number of rows/cols of the subplot grid.

        sharex, sharey : bool or {'none', 'all', 'row', 'col'}, default: False
            Controls sharing of properties among x (`sharex`) or y (`sharey`)
            axes:

                - True or 'all': x- or y-axis will be shared among all
                  subplots.
                - False or 'none': each subplot x- or y-axis will be
                  independent.
                - 'row': each subplot row will share an x- or y-axis.
                - 'col': each subplot column will share an x- or y-axis.

            When subplots have a shared x-axis along a column, only the x tick
            labels of the bottom subplot are visible.  Similarly, when
            subplots have a shared y-axis along a row, only the y tick labels
            of the first column subplot are visible.

        squeeze : bool, default: True
            - If True, extra dimensions are squeezed out from the returned
              axis object:

                - if only one subplot is constructed (nrows=ncols=1), the
                  resulting single Axes object is returned as a scalar.
                - for Nx1 or 1xN subplots, the returned object is a 1D numpy
                  object array of Axes objects are returned as numpy 1D
                  arrays.
                - for NxM, subplots with N>1 and M>1 are returned as a 2D
                  arrays.

            - If False, no squeezing at all is done: the returned Axes object
              is always a 2D array containing Axes instances, even if it ends
              up being 1x1.

        subplot_kw : dict, default: {}
            Dict with keywords passed to the
            :meth:`~matplotlib.figure.Figure.add_subplot` call used to create
            each subplots.

        gridspec_kw : dict, default: {}
            Dict with keywords passed to the
            :class:`~matplotlib.gridspec.GridSpec` constructor used to create
            the grid the subplots are placed on.

        Returns
        -------
        ax : single Axes object or array of Axes objects
            The added axes.  The dimensions of the resulting array can be
            controlled with the squeeze keyword, see above.

        See Also
        --------
        pyplot.subplots : pyplot API; docstring includes examples.
        """

        # for backwards compatibility
        if isinstance(sharex, bool):
            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, int):
                warnings.warn(
                    "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))
        if subplot_kw is None:
            subplot_kw = {}
        if gridspec_kw is None:
            gridspec_kw = {}

        gs = GridSpec(nrows, ncols, **gridspec_kw)

        # Create array to hold all axes.
        axarr = np.empty((nrows, ncols), dtype=object)
        for row in range(nrows):
            for col in range(ncols):
                shared_with = {"none": None, "all": axarr[0, 0],
                               "row": axarr[row, 0], "col": axarr[0, col]}
                subplot_kw["sharex"] = shared_with[sharex]
                subplot_kw["sharey"] = shared_with[sharey]
                axarr[row, col] = self.add_subplot(gs[row, col], **subplot_kw)

        # turn off redundant tick labeling
        if sharex in ["col", "all"]:
            # turn off all but the bottom row
            for ax in axarr[:-1, :].flat:
                ax.xaxis.set_tick_params(which='both',
                                         labelbottom=False, labeltop=False)
                ax.xaxis.offsetText.set_visible(False)
        if sharey in ["row", "all"]:
            # turn off all but the first column
            for ax in axarr[:, 1:].flat:
                ax.yaxis.set_tick_params(which='both',
                                         labelleft=False, labelright=False)
                ax.yaxis.offsetText.set_visible(False)

        if squeeze:
            # Discarding unneeded dimensions that equal 1.  If we only have one
            # subplot, just return it instead of a 1-element array.
            return axarr.item() if axarr.size == 1 else axarr.squeeze()
        else:
            # Returned axis array will be always 2-d, even if nrows=ncols=1.
            return axarr

    def __remove_ax(self, ax):
        def _reset_loc_form(axis):
            axis.set_major_formatter(axis.get_major_formatter())
            axis.set_major_locator(axis.get_major_locator())
            axis.set_minor_formatter(axis.get_minor_formatter())
            axis.set_minor_locator(axis.get_minor_locator())

        def _break_share_link(ax, grouper):
            siblings = grouper.get_siblings(ax)
            if len(siblings) > 1:
                grouper.remove(ax)
                for last_ax in siblings:
                    if ax is last_ax:
                        continue
                    return last_ax
            return None

        self.delaxes(ax)
        last_ax = _break_share_link(ax, ax._shared_y_axes)
        if last_ax is not None:
            _reset_loc_form(last_ax.yaxis)

        last_ax = _break_share_link(ax, ax._shared_x_axes)
        if last_ax is not None:
            _reset_loc_form(last_ax.xaxis)

    def clf(self, keep_observers=False):
        """
        Clear the figure.

        Set *keep_observers* to True if, for example,
        a gui widget is tracking the axes in the figure.
        """
        self.suppressComposite = None
        self.callbacks = cbook.CallbackRegistry()

        for ax in tuple(self.axes):  # Iterate over the copy.
            ax.cla()
            self.delaxes(ax)         # removes ax from self._axstack

        toolbar = getattr(self.canvas, 'toolbar', None)
        if toolbar is not None:
            toolbar.update()
        self._axstack.clear()
        self.artists = []
        self.lines = []
        self.patches = []
        self.texts = []
        self.images = []
        self.legends = []
        if not keep_observers:
            self._axobservers = []
        self._suptitle = None
        self.stale = True

    def clear(self, keep_observers=False):
        """
        Clear the figure -- synonym for :meth:`clf`.
        """
        self.clf(keep_observers=keep_observers)

    @allow_rasterization
    def draw(self, renderer):
        """
        Render the figure using :class:`matplotlib.backend_bases.RendererBase`
        instance *renderer*.
        """

        # draw the figure bounding box, perhaps none for white figure
        if not self.get_visible():
            return

        artists = sorted(
            (artist for artist in (self.patches + self.lines + self.artists
                                   + self.images + self.axes + self.texts
                                   + self.legends)
             if not artist.get_animated()),
            key=lambda artist: artist.get_zorder())

        try:
            renderer.open_group('figure')
            if self.get_tight_layout() and self.axes:
                try:
                    self.tight_layout(renderer, **self._tight_parameters)
                except ValueError:
                    pass
                    # ValueError can occur when resizing a window.

            if self.frameon:
                self.patch.draw(renderer)

            mimage._draw_list_compositing_images(
                renderer, self, artists, self.suppressComposite)

            renderer.close_group('figure')
        finally:
            self.stale = False

        self._cachedRenderer = renderer
        self.canvas.draw_event(renderer)

    def draw_artist(self, a):
        """
        draw :class:`matplotlib.artist.Artist` instance *a* only --
        this is available only after the figure is drawn
        """
        if self._cachedRenderer is None:
            msg = ('draw_artist can only be used after an initial draw which'
                   ' caches the render')
            raise AttributeError(msg)
        a.draw(self._cachedRenderer)

    def get_axes(self):
        return self.axes

    @docstring.dedent_interpd
    def legend(self, *args, **kwargs):
        """
        Place a legend on the figure.

        To make a legend from existing artists on every axes::

          legend()

        To make a legend for a list of lines and labels::

          legend( (line1, line2, line3),
                  ('label1', 'label2', 'label3'),
                  loc='upper right')

        These can also be specified by keyword::

          legend(handles=(line1, line2, line3),
                labels=('label1', 'label2', 'label3'),
                loc='upper right')

        Parameters
        ----------

        loc : int or string or pair of floats, default: 'upper right'
            The location of the legend. Possible codes are:

                ===============   =============
                Location String   Location Code
                ===============   =============
                'best'            0
                'upper right'     1
                'upper left'      2
                'lower left'      3
                'lower right'     4
                'right'           5
                'center left'     6
                'center right'    7
                'lower center'    8
                'upper center'    9
                'center'          10
                ===============   =============


            Alternatively can be a 2-tuple giving ``x, y`` of the lower-left
            corner of the legend in axes coordinates (in which case
            ``bbox_to_anchor`` will be ignored).

        bbox_to_anchor : `~.BboxBase` or pair of floats
            Specify any arbitrary location for the legend in `bbox_transform`
            coordinates (default Axes coordinates).

            For example, to put the legend's upper right hand corner in the
            center of the axes the following keywords can be used::

               loc='upper right', bbox_to_anchor=(0.5, 0.5)

        ncol : integer
            The number of columns that the legend has. Default is 1.

        prop : None or :class:`matplotlib.font_manager.FontProperties` or dict
            The font properties of the legend. If None (default), the current
            :data:`matplotlib.rcParams` will be used.

        fontsize : int or float or {'xx-small', 'x-small', 'small', 'medium', \
'large', 'x-large', 'xx-large'}
            Controls the font size of the legend. If the value is numeric the
            size will be the absolute font size in points. String values are
            relative to the current default font size. This argument is only
            used if `prop` is not specified.

        numpoints : None or int
            The number of marker points in the legend when creating a legend
            entry for a line/:class:`matplotlib.lines.Line2D`.
            Default is ``None`` which will take the value from the
            ``legend.numpoints`` :data:`rcParam<matplotlib.rcParams>`.

        scatterpoints : None or int
            The number of marker points in the legend when creating a legend
            entry for a scatter plot/
            :class:`matplotlib.collections.PathCollection`.
            Default is ``None`` which will take the value from the
            ``legend.scatterpoints`` :data:`rcParam<matplotlib.rcParams>`.

        scatteryoffsets : iterable of floats
            The vertical offset (relative to the font size) for the markers
            created for a scatter plot legend entry. 0.0 is at the base the
            legend text, and 1.0 is at the top. To draw all markers at the
            same height, set to ``[0.5]``. Default ``[0.375, 0.5, 0.3125]``.

        markerscale : None or int or float
            The relative size of legend markers compared with the originally
            drawn ones. Default is ``None`` which will take the value from
            the ``legend.markerscale`` :data:`rcParam <matplotlib.rcParams>`.

        markerfirst : bool
            If *True*, legend marker is placed to the left of the legend label.
            If *False*, legend marker is placed to the right of the legend
            label.
            Default is *True*.

        frameon : None or bool
            Control whether the legend should be drawn on a patch (frame).
            Default is ``None`` which will take the value from the
            ``legend.frameon`` :data:`rcParam<matplotlib.rcParams>`.

        fancybox : None or bool
            Control whether round edges should be enabled around
            the :class:`~matplotlib.patches.FancyBboxPatch` which
            makes up the legend's background.
            Default is ``None`` which will take the value from the
            ``legend.fancybox`` :data:`rcParam<matplotlib.rcParams>`.

        shadow : None or bool
            Control whether to draw a shadow behind the legend.
            Default is ``None`` which will take the value from the
            ``legend.shadow`` :data:`rcParam<matplotlib.rcParams>`.

        framealpha : None or float
            Control the alpha transparency of the legend's background.
            Default is ``None`` which will take the value from the
            ``legend.framealpha`` :data:`rcParam<matplotlib.rcParams>`.
            If shadow is activated and framealpha is ``None`` the
            default value is being ignored.

        facecolor : None or "inherit" or a color spec
            Control the legend's background color.
            Default is ``None`` which will take the value from the
            ``legend.facecolor`` :data:`rcParam<matplotlib.rcParams>`.
            If ``"inherit"``, it will take the ``axes.facecolor``
            :data:`rcParam<matplotlib.rcParams>`.

        edgecolor : None or "inherit" or a color spec
            Control the legend's background patch edge color.
            Default is ``None`` which will take the value from the
            ``legend.edgecolor`` :data:`rcParam<matplotlib.rcParams>`.
            If ``"inherit"``, it will take the ``axes.edgecolor``
            :data:`rcParam<matplotlib.rcParams>`.

        mode : {"expand", None}
            If `mode` is set to ``"expand"`` the legend will be horizontally
            expanded to fill the axes area (or `bbox_to_anchor` if defines
            the legend's size).

        bbox_transform : None or :class:`matplotlib.transforms.Transform`
            The transform for the bounding box (`bbox_to_anchor`). For a value
            of ``None`` (default) the Axes'
            :data:`~matplotlib.axes.Axes.transAxes` transform will be used.

        title : str or None
            The legend's title. Default is no title (``None``).

        borderpad : float or None
            The fractional whitespace inside the legend border.
            Measured in font-size units.
            Default is ``None`` which will take the value from the
            ``legend.borderpad`` :data:`rcParam<matplotlib.rcParams>`.

        labelspacing : float or None
            The vertical space between the legend entries.
            Measured in font-size units.
            Default is ``None`` which will take the value from the
            ``legend.labelspacing`` :data:`rcParam<matplotlib.rcParams>`.

        handlelength : float or None
            The length of the legend handles.
            Measured in font-size units.
            Default is ``None`` which will take the value from the
            ``legend.handlelength`` :data:`rcParam<matplotlib.rcParams>`.

        handletextpad : float or None
            The pad between the legend handle and text.
            Measured in font-size units.
            Default is ``None`` which will take the value from the
            ``legend.handletextpad`` :data:`rcParam<matplotlib.rcParams>`.

        borderaxespad : float or None
            The pad between the axes and legend border.
            Measured in font-size units.
            Default is ``None`` which will take the value from the
            ``legend.borderaxespad`` :data:`rcParam<matplotlib.rcParams>`.

        columnspacing : float or None
            The spacing between columns.
            Measured in font-size units.
            Default is ``None`` which will take the value from the
            ``legend.columnspacing`` :data:`rcParam<matplotlib.rcParams>`.

        handler_map : dict or None
            The custom dictionary mapping instances or types to a legend
            handler. This `handler_map` updates the default handler map
            found at :func:`matplotlib.legend.Legend.get_legend_handler_map`.

        Returns
        -------
        :class:`matplotlib.legend.Legend` instance

        Notes
        -----
        Not all kinds of artist are supported by the legend command. See
        :ref:`sphx_glr_tutorials_intermediate_legend_guide.py` for details.
        """

        handles, labels, extra_args, kwargs = mlegend._parse_legend_args(
                self.axes,
                *args,
                **kwargs)
        # check for third arg
        if len(extra_args):
            # cbook.warn_deprecated(
            #     "2.1",
            #     "Figure.legend will accept no more than two "
            #     "positional arguments in the future.  Use "
            #     "'fig.legend(handles, labels, loc=location)' "
            #     "instead.")
            # kwargs['loc'] = extra_args[0]
            # extra_args = extra_args[1:]
            pass
        l = mlegend.Legend(self, handles, labels, *extra_args, **kwargs)
        self.legends.append(l)
        l._remove_method = lambda h: self.legends.remove(h)
        self.stale = True
        return l

    @docstring.dedent_interpd
    def text(self, x, y, s, *args, **kwargs):
        """
        Add text to figure.

        Call signature::

          text(x, y, s, fontdict=None, **kwargs)

        Add text to figure at location *x*, *y* (relative 0-1
        coords). See :func:`~matplotlib.pyplot.text` for the meaning
        of the other arguments.

        kwargs control the :class:`~matplotlib.text.Text` properties:

        %(Text)s
        """

        override = _process_text_args({}, *args, **kwargs)
        t = Text(x=x, y=y, text=s)

        t.update(override)
        self._set_artist_props(t)
        self.texts.append(t)
        t._remove_method = lambda h: self.texts.remove(h)
        self.stale = True
        return t

    def _set_artist_props(self, a):
        if a != self:
            a.set_figure(self)
        a.stale_callback = _stale_figure_callback
        a.set_transform(self.transFigure)

    @docstring.dedent_interpd
    def gca(self, **kwargs):
        """
        Get the current axes, creating one if necessary

        The following kwargs are supported for ensuring the returned axes
        adheres to the given projection etc., and for axes creation if
        the active axes does not exist:

        %(Axes)s

        """
        ckey, cax = self._axstack.current_key_axes()
        # if there exists an axes on the stack see if it maches
        # the desired axes configuration
        if cax is not None:

            # if no kwargs are given just return the current axes
            # this is a convenience for gca() on axes such as polar etc.
            if not kwargs:
                return cax

            # if the user has specified particular projection detail
            # then build up a key which can represent this
            else:
                # we don't want to modify the original kwargs
                # so take a copy so that we can do what we like to it
                kwargs_copy = kwargs.copy()
                projection_class, _, key = process_projection_requirements(
                    self, **kwargs_copy)

                # let the returned axes have any gridspec by removing it from
                # the key
                ckey = ckey[1:]
                key = key[1:]

                # if the cax matches this key then return the axes, otherwise
                # continue and a new axes will be created
                if key == ckey and isinstance(cax, projection_class):
                    return cax
                else:
                    warnings.warn('Requested projection is different from '
                                  'current axis projection, creating new axis '
                                  'with requested projection.', stacklevel=2)

        # no axes found, so create one which spans the figure
        return self.add_subplot(1, 1, 1, **kwargs)

    def sca(self, a):
        'Set the current axes to be a and return a'
        self._axstack.bubble(a)
        for func in self._axobservers:
            func(self)
        return a

    def _gci(self):
        """
        helper for :func:`~matplotlib.pyplot.gci`;
        do not use elsewhere.
        """
        # Look first for an image in the current Axes:
        cax = self._axstack.current_key_axes()[1]
        if cax is None:
            return None
        im = cax._gci()
        if im is not None:
            return im

        # If there is no image in the current Axes, search for
        # one in a previously created Axes.  Whether this makes
        # sense is debatable, but it is the documented behavior.
        for ax in reversed(self.axes):
            im = ax._gci()
            if im is not None:
                return im
        return None

    def __getstate__(self):
        state = super(Figure, self).__getstate__()
        # the axobservers cannot currently be pickled.
        # Additionally, the canvas cannot currently be pickled, but this has
        # the benefit of meaning that a figure can be detached from one canvas,
        # and re-attached to another.
        for attr_to_pop in ('_axobservers', 'show',
                            'canvas', '_cachedRenderer'):
            state.pop(attr_to_pop, None)

        # add version information to the state
        state['__mpl_version__'] = _mpl_version

        # check to see if the figure has a manager and whether it is registered
        # with pyplot
        if getattr(self.canvas, 'manager', None) is not None:
            manager = self.canvas.manager
            import matplotlib._pylab_helpers
            if manager in list(six.itervalues(
                    matplotlib._pylab_helpers.Gcf.figs)):
                state['_restore_to_pylab'] = True

        return state

    def __setstate__(self, state):
        version = state.pop('__mpl_version__')
        restore_to_pylab = state.pop('_restore_to_pylab', False)

        if version != _mpl_version:
            import warnings
            warnings.warn("This figure was saved with matplotlib version %s "
                          "and is unlikely to function correctly." %
                          (version, ))

        self.__dict__ = state

        # re-initialise some of the unstored state information
        self._axobservers = []
        self.canvas = None

        if restore_to_pylab:
            # lazy import to avoid circularity
            import matplotlib.pyplot as plt
            import matplotlib._pylab_helpers as pylab_helpers
            allnums = plt.get_fignums()
            num = max(allnums) + 1 if allnums else 1
            mgr = plt._backend_mod.new_figure_manager_given_figure(num, self)

            # XXX The following is a copy and paste from pyplot. Consider
            # factoring to pylab_helpers

            if self.get_label():
                mgr.set_window_title(self.get_label())

            # make this figure current on button press event
            def make_active(event):
                pylab_helpers.Gcf.set_active(mgr)

            mgr._cidgcf = mgr.canvas.mpl_connect('button_press_event',
                                                 make_active)

            pylab_helpers.Gcf.set_active(mgr)
            self.number = num

            plt.draw_if_interactive()
        self.stale = True

    def add_axobserver(self, func):
        'whenever the axes state change, ``func(self)`` will be called'
        self._axobservers.append(func)

    def savefig(self, fname, **kwargs):
        """
        Save the current figure.

        Call signature::

          savefig(fname, dpi=None, facecolor='w', edgecolor='w',
                  orientation='portrait', papertype=None, format=None,
                  transparent=False, bbox_inches=None, pad_inches=0.1,
                  frameon=None)

        The output formats available depend on the backend being used.

        Parameters
        ----------

        fname : str or file-like object
            A string containing a path to a filename, or a Python
            file-like object, or possibly some backend-dependent object
            such as :class:`~matplotlib.backends.backend_pdf.PdfPages`.

            If *format* is *None* and *fname* is a string, the output
            format is deduced from the extension of the filename. If
            the filename has no extension, the value of the rc parameter
            ``savefig.format`` is used.

            If *fname* is not a string, remember to specify *format* to
            ensure that the correct backend is used.

        Other Parameters
        ----------------

        dpi : [ *None* | scalar > 0 | 'figure']
            The resolution in dots per inch.  If *None* it will default to
            the value ``savefig.dpi`` in the matplotlibrc file. If 'figure'
            it will set the dpi to be the value of the figure.

        facecolor : color spec or None, optional
            the facecolor of the figure; if None, defaults to savefig.facecolor

        edgecolor : color spec or None, optional
            the edgecolor of the figure; if None, defaults to savefig.edgecolor

        orientation : {'landscape', 'portrait'}
            not supported on all backends; currently only on postscript output

        papertype : str
            One of 'letter', 'legal', 'executive', 'ledger', 'a0' through
            'a10', 'b0' through 'b10'. Only supported for postscript
            output.

        format : str
            One of the file extensions supported by the active
            backend.  Most backends support png, pdf, ps, eps and svg.

        transparent : bool
            If *True*, the axes patches will all be transparent; the
            figure patch will also be transparent unless facecolor
            and/or edgecolor are specified via kwargs.
            This is useful, for example, for displaying
            a plot on top of a colored background on a web page.  The
            transparency of these patches will be restored to their
            original values upon exit of this function.

        frameon : bool
            If *True*, the figure patch will be colored, if *False*, the
            figure background will be transparent.  If not provided, the
            rcParam 'savefig.frameon' will be used.

        bbox_inches : str or `~matplotlib.transforms.Bbox`, optional
            Bbox in inches. Only the given portion of the figure is
            saved. If 'tight', try to figure out the tight bbox of
            the figure. If None, use savefig.bbox

        pad_inches : scalar, optional
            Amount of padding around the figure when bbox_inches is
            'tight'. If None, use savefig.pad_inches

        bbox_extra_artists : list of `~matplotlib.artist.Artist`, optional
            A list of extra artists that will be considered when the
            tight bbox is calculated.

        """
        kwargs.setdefault('dpi', rcParams['savefig.dpi'])
        frameon = kwargs.pop('frameon', rcParams['savefig.frameon'])
        transparent = kwargs.pop('transparent',
                                 rcParams['savefig.transparent'])

        if transparent:
            kwargs.setdefault('facecolor', 'none')
            kwargs.setdefault('edgecolor', 'none')
            original_axes_colors = []
            for ax in self.axes:
                patch = ax.patch
                original_axes_colors.append((patch.get_facecolor(),
                                             patch.get_edgecolor()))
                patch.set_facecolor('none')
                patch.set_edgecolor('none')
        else:
            kwargs.setdefault('facecolor', rcParams['savefig.facecolor'])
            kwargs.setdefault('edgecolor', rcParams['savefig.edgecolor'])

        if frameon:
            original_frameon = self.get_frameon()
            self.set_frameon(frameon)

        self.canvas.print_figure(fname, **kwargs)

        if frameon:
            self.set_frameon(original_frameon)

        if transparent:
            for ax, cc in zip(self.axes, original_axes_colors):
                ax.patch.set_facecolor(cc[0])
                ax.patch.set_edgecolor(cc[1])

    @docstring.dedent_interpd
    def colorbar(self, mappable, cax=None, ax=None, use_gridspec=True, **kw):
        """
        Create a colorbar for a ScalarMappable instance, *mappable*.

        Documentation for the pylab thin wrapper:
        %(colorbar_doc)s
        """
        if ax is None:
            ax = self.gca()

        # Store the value of gca so that we can set it back later on.
        current_ax = self.gca()

        if cax is None:
            if use_gridspec and isinstance(ax, SubplotBase):
                cax, kw = cbar.make_axes_gridspec(ax, **kw)
            else:
                cax, kw = cbar.make_axes(ax, **kw)
        cax._hold = True
        cb = cbar.colorbar_factory(cax, mappable, **kw)

        self.sca(current_ax)
        self.stale = True
        return cb

    def subplots_adjust(self, *args, **kwargs):
        """
        Call signature::

          subplots_adjust(left=None, bottom=None, right=None, top=None,
                              wspace=None, hspace=None)

        Update the :class:`SubplotParams` with *kwargs* (defaulting to rc when
        *None*) and update the subplot locations

        """
        self.subplotpars.update(*args, **kwargs)
        for ax in self.axes:
            if not isinstance(ax, SubplotBase):
                # Check if sharing a subplots axis
                if isinstance(ax._sharex, SubplotBase):
                    ax._sharex.update_params()
                    ax.set_position(ax._sharex.figbox)
                elif isinstance(ax._sharey, SubplotBase):
                    ax._sharey.update_params()
                    ax.set_position(ax._sharey.figbox)
            else:
                ax.update_params()
                ax.set_position(ax.figbox)
        self.stale = True

    def ginput(self, n=1, timeout=30, show_clicks=True, mouse_add=1,
               mouse_pop=3, mouse_stop=2):
        """
        Blocking call to interact with a figure.

        Wait until the user clicks *n* times on the figure, and return the
        coordinates of each click in a list.

        The buttons used for the various actions (adding points, removing
        points, terminating the inputs) can be overridden via the
        arguments *mouse_add*, *mouse_pop* and *mouse_stop*, that give
        the associated mouse button: 1 for left, 2 for middle, 3 for
        right.

        Parameters
        ----------
        n : int, optional, default: 1
            Number of mouse clicks to accumulate. If negative, accumulate
            clicks until the input is terminated manually.
        timeout : scalar, optional, default: 30
            Number of seconds to wait before timing out. If zero or negative
            will never timeout.
        show_clicks : bool, optional, default: False
            If True, show a red cross at the location of each click.
        mouse_add : int, one of (1, 2, 3), optional, default: 1 (left click)
            Mouse button used to add points.
        mouse_pop : int, one of (1, 2, 3), optional, default: 3 (right click)
            Mouse button used to remove the most recently added point.
        mouse_stop : int, one of (1, 2, 3), optional, default: 2 (middle click)
            Mouse button used to stop input.

        Returns
        -------
        points : list of tuples
            A list of the clicked (x, y) coordinates.

        Notes
        -----
        The keyboard can also be used to select points in case your mouse
        does not have one or more of the buttons.  The delete and backspace
        keys act like right clicking (i.e., remove last point), the enter key
        terminates input and any other key (not already used by the window
        manager) selects a point.
        """

        blocking_mouse_input = BlockingMouseInput(self,
                                                  mouse_add=mouse_add,
                                                  mouse_pop=mouse_pop,
                                                  mouse_stop=mouse_stop)
        return blocking_mouse_input(n=n, timeout=timeout,
                                    show_clicks=show_clicks)

    def waitforbuttonpress(self, timeout=-1):
        """
        Blocking call to interact with the figure.

        This will return True is a key was pressed, False if a mouse
        button was pressed and None if *timeout* was reached without
        either being pressed.

        If *timeout* is negative, does not timeout.
        """

        blocking_input = BlockingKeyMouseInput(self)
        return blocking_input(timeout=timeout)

    def get_default_bbox_extra_artists(self):
        bbox_artists = [artist for artist in self.get_children()
                        if artist.get_visible()]
        for ax in self.axes:
            if ax.get_visible():
                bbox_artists.extend(ax.get_default_bbox_extra_artists())
        # we don't want the figure's patch to influence the bbox calculation
        bbox_artists.remove(self.patch)
        return bbox_artists

    def get_tightbbox(self, renderer):
        """
        Return a (tight) bounding box of the figure in inches.

        It only accounts axes title, axis labels, and axis
        ticklabels. Needs improvement.
        """

        bb = []
        for ax in self.axes:
            if ax.get_visible():
                bb.append(ax.get_tightbbox(renderer))

        if len(bb) == 0:
            return self.bbox_inches

        _bbox = Bbox.union([b for b in bb if b.width != 0 or b.height != 0])

        bbox_inches = TransformedBbox(_bbox,
                                      Affine2D().scale(1. / self.dpi))

        return bbox_inches

    def tight_layout(self, renderer=None, pad=1.08, h_pad=None, w_pad=None,
                     rect=None):
        """
        Adjust subplot parameters to give specified padding.

        Parameters
        ----------

        pad : float
            padding between the figure edge and the edges of subplots,
            as a fraction of the font-size.

        h_pad, w_pad : float, optional
            padding (height/width) between edges of adjacent subplots.
            Defaults to `pad_inches`.

        rect : tuple (left, bottom, right, top), optional
            a rectangle (left, bottom, right, top) in the normalized
            figure coordinate that the whole subplots area (including
            labels) will fit into. Default is (0, 0, 1, 1).
        """

        from .tight_layout import (
            get_renderer, get_subplotspec_list, get_tight_layout_figure)

        subplotspec_list = get_subplotspec_list(self.axes)
        if None in subplotspec_list:
            warnings.warn("This figure includes Axes that are not compatible "
                          "with tight_layout, so results might be incorrect.")

        if renderer is None:
            renderer = get_renderer(self)

        kwargs = get_tight_layout_figure(
            self, self.axes, subplotspec_list, renderer,
            pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
        self.subplots_adjust(**kwargs)


def figaspect(arg):
    """
    Create a figure with specified aspect ratio.  If *arg* is a number,
    use that aspect ratio.  If *arg* is an array, figaspect will
    determine the width and height for a figure that would fit array
    preserving aspect ratio.  The figure width, height in inches are
    returned.  Be sure to create an axes with equal with and height,
    e.g.,

    Example usage::

      # make a figure twice as tall as it is wide
      w, h = figaspect(2.)
      fig = Figure(figsize=(w,h))
      ax = fig.add_axes([0.1, 0.1, 0.8, 0.8])
      ax.imshow(A, **kwargs)


      # make a figure with the proper aspect for an array
      A = rand(5,3)
      w, h = figaspect(A)
      fig = Figure(figsize=(w,h))
      ax = fig.add_axes([0.1, 0.1, 0.8, 0.8])
      ax.imshow(A, **kwargs)

    Thanks to Fernando Perez for this function
    """

    isarray = hasattr(arg, 'shape') and not np.isscalar(arg)

    # min/max sizes to respect when autoscaling.  If John likes the idea, they
    # could become rc parameters, for now they're hardwired.
    figsize_min = np.array((4.0, 2.0))  # min length for width/height
    figsize_max = np.array((16.0, 16.0))  # max length for width/height

    # Extract the aspect ratio of the array
    if isarray:
        nr, nc = arg.shape[:2]
        arr_ratio = float(nr) / nc
    else:
        arr_ratio = float(arg)

    # Height of user figure defaults
    fig_height = rcParams['figure.figsize'][1]

    # New size for the figure, keeping the aspect ratio of the caller
    newsize = np.array((fig_height / arr_ratio, fig_height))

    # Sanity checks, don't drop either dimension below figsize_min
    newsize /= min(1.0, *(newsize / figsize_min))

    # Avoid humongous windows as well
    newsize /= max(1.0, *(newsize / figsize_max))

    # Finally, if we have a really funky aspect ratio, break it but respect
    # the min/max dimensions (we don't want figures 10 feet tall!)
    newsize = np.clip(newsize, figsize_min, figsize_max)
    return newsize

docstring.interpd.update(Figure=martist.kwdoc(Figure))
