artists.ipynb

{
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  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "%matplotlib inline"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "\n",
    "# Artist tutorial\n",
    "\n",
    "\n",
    "Using Artist objects to render on the canvas.\n",
    "\n",
    "There are three layers to the matplotlib API.\n",
    "\n",
    "* the :class:`matplotlib.backend_bases.FigureCanvas` is the area onto which\n",
    "  the figure is drawn\n",
    "* the :class:`matplotlib.backend_bases.Renderer` is\n",
    "  the object which knows how to draw on the\n",
    "  :class:`~matplotlib.backend_bases.FigureCanvas`\n",
    "* and the :class:`matplotlib.artist.Artist` is the object that knows how to use\n",
    "  a renderer to paint onto the canvas.\n",
    "\n",
    "The :class:`~matplotlib.backend_bases.FigureCanvas` and\n",
    ":class:`~matplotlib.backend_bases.Renderer` handle all the details of\n",
    "talking to user interface toolkits like `wxPython\n",
    "<https://www.wxpython.org>`_ or drawing languages like PostScript®, and\n",
    "the ``Artist`` handles all the high level constructs like representing\n",
    "and laying out the figure, text, and lines.  The typical user will\n",
    "spend 95% of their time working with the ``Artists``.\n",
    "\n",
    "There are two types of ``Artists``: primitives and containers.  The primitives\n",
    "represent the standard graphical objects we want to paint onto our canvas:\n",
    ":class:`~matplotlib.lines.Line2D`, :class:`~matplotlib.patches.Rectangle`,\n",
    ":class:`~matplotlib.text.Text`, :class:`~matplotlib.image.AxesImage`, etc., and\n",
    "the containers are places to put them (:class:`~matplotlib.axis.Axis`,\n",
    ":class:`~matplotlib.axes.Axes` and :class:`~matplotlib.figure.Figure`).  The\n",
    "standard use is to create a :class:`~matplotlib.figure.Figure` instance, use\n",
    "the ``Figure`` to create one or more :class:`~matplotlib.axes.Axes` or\n",
    ":class:`~matplotlib.axes.Subplot` instances, and use the ``Axes`` instance\n",
    "helper methods to create the primitives.  In the example below, we create a\n",
    "``Figure`` instance using :func:`matplotlib.pyplot.figure`, which is a\n",
    "convenience method for instantiating ``Figure`` instances and connecting them\n",
    "with your user interface or drawing toolkit ``FigureCanvas``.  As we will\n",
    "discuss below, this is not necessary -- you can work directly with PostScript,\n",
    "PDF Gtk+, or wxPython ``FigureCanvas`` instances, instantiate your ``Figures``\n",
    "directly and connect them yourselves -- but since we are focusing here on the\n",
    "``Artist`` API we'll let :mod:`~matplotlib.pyplot` handle some of those details\n",
    "for us::\n",
    "\n",
    "    import matplotlib.pyplot as plt\n",
    "    fig = plt.figure()\n",
    "    ax = fig.add_subplot(2, 1, 1) # two rows, one column, first plot\n",
    "\n",
    "The :class:`~matplotlib.axes.Axes` is probably the most important\n",
    "class in the matplotlib API, and the one you will be working with most\n",
    "of the time.  This is because the ``Axes`` is the plotting area into\n",
    "which most of the objects go, and the ``Axes`` has many special helper\n",
    "methods (:meth:`~matplotlib.axes.Axes.plot`,\n",
    ":meth:`~matplotlib.axes.Axes.text`,\n",
    ":meth:`~matplotlib.axes.Axes.hist`,\n",
    ":meth:`~matplotlib.axes.Axes.imshow`) to create the most common\n",
    "graphics primitives (:class:`~matplotlib.lines.Line2D`,\n",
    ":class:`~matplotlib.text.Text`,\n",
    ":class:`~matplotlib.patches.Rectangle`,\n",
    ":class:`~matplotlib.image.AxesImage`, respectively).  These helper methods\n",
    "will take your data (e.g., ``numpy`` arrays and strings) and create\n",
    "primitive ``Artist`` instances as needed (e.g., ``Line2D``), add them to\n",
    "the relevant containers, and draw them when requested.  Most of you\n",
    "are probably familiar with the :class:`~matplotlib.axes.Subplot`,\n",
    "which is just a special case of an ``Axes`` that lives on a regular\n",
    "rows by columns grid of ``Subplot`` instances.  If you want to create\n",
    "an ``Axes`` at an arbitrary location, simply use the\n",
    ":meth:`~matplotlib.figure.Figure.add_axes` method which takes a list\n",
    "of ``[left, bottom, width, height]`` values in 0-1 relative figure\n",
    "coordinates::\n",
    "\n",
    "    fig2 = plt.figure()\n",
    "    ax2 = fig2.add_axes([0.15, 0.1, 0.7, 0.3])\n",
    "\n",
    "Continuing with our example::\n",
    "\n",
    "    import numpy as np\n",
    "    t = np.arange(0.0, 1.0, 0.01)\n",
    "    s = np.sin(2*np.pi*t)\n",
    "    line, = ax.plot(t, s, color='blue', lw=2)\n",
    "\n",
    "In this example, ``ax`` is the ``Axes`` instance created by the\n",
    "``fig.add_subplot`` call above (remember ``Subplot`` is just a\n",
    "subclass of ``Axes``) and when you call ``ax.plot``, it creates a\n",
    "``Line2D`` instance and adds it to the :attr:`Axes.lines\n",
    "<matplotlib.axes.Axes.lines>` list.  In the interactive `ipython\n",
    "<http://ipython.org/>`_ session below, you can see that the\n",
    "``Axes.lines`` list is length one and contains the same line that was\n",
    "returned by the ``line, = ax.plot...`` call:\n",
    "\n",
    ".. sourcecode:: ipython\n",
    "\n",
    "    In [101]: ax.lines[0]\n",
    "    Out[101]: <matplotlib.lines.Line2D instance at 0x19a95710>\n",
    "\n",
    "    In [102]: line\n",
    "    Out[102]: <matplotlib.lines.Line2D instance at 0x19a95710>\n",
    "\n",
    "If you make subsequent calls to ``ax.plot`` (and the hold state is \"on\"\n",
    "which is the default) then additional lines will be added to the list.\n",
    "You can remove lines later simply by calling the list methods; either\n",
    "of these will work::\n",
    "\n",
    "    del ax.lines[0]\n",
    "    ax.lines.remove(line)  # one or the other, not both!\n",
    "\n",
    "The Axes also has helper methods to configure and decorate the x-axis\n",
    "and y-axis tick, tick labels and axis labels::\n",
    "\n",
    "    xtext = ax.set_xlabel('my xdata') # returns a Text instance\n",
    "    ytext = ax.set_ylabel('my ydata')\n",
    "\n",
    "When you call :meth:`ax.set_xlabel <matplotlib.axes.Axes.set_xlabel>`,\n",
    "it passes the information on the :class:`~matplotlib.text.Text`\n",
    "instance of the :class:`~matplotlib.axis.XAxis`.  Each ``Axes``\n",
    "instance contains an :class:`~matplotlib.axis.XAxis` and a\n",
    ":class:`~matplotlib.axis.YAxis` instance, which handle the layout and\n",
    "drawing of the ticks, tick labels and axis labels.\n",
    "\n",
    "Try creating the figure below.\n"
   ]
  },
  {
   "cell_type": "code",
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   "metadata": {},
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   "source": [
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "fig = plt.figure()\n",
    "fig.subplots_adjust(top=0.8)\n",
    "ax1 = fig.add_subplot(211)\n",
    "ax1.set_ylabel('volts')\n",
    "ax1.set_title('a sine wave')\n",
    "\n",
    "t = np.arange(0.0, 1.0, 0.01)\n",
    "s = np.sin(2*np.pi*t)\n",
    "line, = ax1.plot(t, s, color='blue', lw=2)\n",
    "\n",
    "# Fixing random state for reproducibility\n",
    "np.random.seed(19680801)\n",
    "\n",
    "ax2 = fig.add_axes([0.15, 0.1, 0.7, 0.3])\n",
    "n, bins, patches = ax2.hist(np.random.randn(1000), 50,\n",
    "                            facecolor='yellow', edgecolor='yellow')\n",
    "ax2.set_xlabel('time (s)')\n",
    "\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "\n",
    "Customizing your objects\n",
    "========================\n",
    "\n",
    "Every element in the figure is represented by a matplotlib\n",
    ":class:`~matplotlib.artist.Artist`, and each has an extensive list of\n",
    "properties to configure its appearance.  The figure itself contains a\n",
    ":class:`~matplotlib.patches.Rectangle` exactly the size of the figure,\n",
    "which you can use to set the background color and transparency of the\n",
    "figures.  Likewise, each :class:`~matplotlib.axes.Axes` bounding box\n",
    "(the standard white box with black edges in the typical matplotlib\n",
    "plot, has a ``Rectangle`` instance that determines the color,\n",
    "transparency, and other properties of the Axes.  These instances are\n",
    "stored as member variables :attr:`Figure.patch\n",
    "<matplotlib.figure.Figure.patch>` and :attr:`Axes.patch\n",
    "<matplotlib.axes.Axes.patch>` (\"Patch\" is a name inherited from\n",
    "MATLAB, and is a 2D \"patch\" of color on the figure, e.g., rectangles,\n",
    "circles and polygons).  Every matplotlib ``Artist`` has the following\n",
    "properties\n",
    "\n",
    "==========  =================================================================\n",
    "Property    Description\n",
    "==========  =================================================================\n",
    "alpha       The transparency - a scalar from 0-1\n",
    "animated    A boolean that is used to facilitate animated drawing\n",
    "axes        The axes that the Artist lives in, possibly None\n",
    "clip_box    The bounding box that clips the Artist\n",
    "clip_on     Whether clipping is enabled\n",
    "clip_path   The path the artist is clipped to\n",
    "contains    A picking function to test whether the artist contains the pick\n",
    "            point\n",
    "figure      The figure instance the artist lives in, possibly None\n",
    "label       A text label (e.g., for auto-labeling)\n",
    "picker      A python object that controls object picking\n",
    "transform   The transformation\n",
    "visible     A boolean whether the artist should be drawn\n",
    "zorder      A number which determines the drawing order\n",
    "rasterized  Boolean; Turns vectors into raster graphics (for compression &\n",
    "            eps transparency)\n",
    "==========  =================================================================\n",
    "\n",
    "Each of the properties is accessed with an old-fashioned setter or\n",
    "getter (yes we know this irritates Pythonistas and we plan to support\n",
    "direct access via properties or traits but it hasn't been done yet).\n",
    "For example, to multiply the current alpha by a half::\n",
    "\n",
    "    a = o.get_alpha()\n",
    "    o.set_alpha(0.5*a)\n",
    "\n",
    "If you want to set a number of properties at once, you can also use\n",
    "the ``set`` method with keyword arguments.  For example::\n",
    "\n",
    "    o.set(alpha=0.5, zorder=2)\n",
    "\n",
    "If you are working interactively at the python shell, a handy way to\n",
    "inspect the ``Artist`` properties is to use the\n",
    ":func:`matplotlib.artist.getp` function (simply\n",
    ":func:`~matplotlib.pyplot.getp` in pyplot), which lists the properties\n",
    "and their values.  This works for classes derived from ``Artist`` as\n",
    "well, e.g., ``Figure`` and ``Rectangle``.  Here are the ``Figure`` rectangle\n",
    "properties mentioned above:\n",
    "\n",
    ".. sourcecode:: ipython\n",
    "\n",
    "    In [149]: matplotlib.artist.getp(fig.patch)\n",
    "\talpha = 1.0\n",
    "\tanimated = False\n",
    "\tantialiased or aa = True\n",
    "\taxes = None\n",
    "\tclip_box = None\n",
    "\tclip_on = False\n",
    "\tclip_path = None\n",
    "\tcontains = None\n",
    "\tedgecolor or ec = w\n",
    "\tfacecolor or fc = 0.75\n",
    "\tfigure = Figure(8.125x6.125)\n",
    "\tfill = 1\n",
    "\thatch = None\n",
    "\theight = 1\n",
    "\tlabel =\n",
    "\tlinewidth or lw = 1.0\n",
    "\tpicker = None\n",
    "\ttransform = <Affine object at 0x134cca84>\n",
    "\tverts = ((0, 0), (0, 1), (1, 1), (1, 0))\n",
    "\tvisible = True\n",
    "\twidth = 1\n",
    "\twindow_extent = <Bbox object at 0x134acbcc>\n",
    "\tx = 0\n",
    "\ty = 0\n",
    "\tzorder = 1\n",
    "\n",
    "The docstrings for all of the classes also contain the ``Artist``\n",
    "properties, so you can consult the interactive \"help\" or the\n",
    "`artist-api` for a listing of properties for a given object.\n",
    "\n",
    "\n",
    "Object containers \n",
    "=================\n",
    "\n",
    "\n",
    "Now that we know how to inspect and set the properties of a given\n",
    "object we want to configure, we need to know how to get at that object.\n",
    "As mentioned in the introduction, there are two kinds of objects:\n",
    "primitives and containers.  The primitives are usually the things you\n",
    "want to configure (the font of a :class:`~matplotlib.text.Text`\n",
    "instance, the width of a :class:`~matplotlib.lines.Line2D`) although\n",
    "the containers also have some properties as well -- for example the\n",
    ":class:`~matplotlib.axes.Axes` :class:`~matplotlib.artist.Artist` is a\n",
    "container that contains many of the primitives in your plot, but it\n",
    "also has properties like the ``xscale`` to control whether the xaxis\n",
    "is 'linear' or 'log'.  In this section we'll review where the various\n",
    "container objects store the ``Artists`` that you want to get at.\n",
    "\n",
    "\n",
    "Figure container\n",
    "----------------\n",
    "\n",
    "The top level container ``Artist`` is the\n",
    ":class:`matplotlib.figure.Figure`, and it contains everything in the\n",
    "figure.  The background of the figure is a\n",
    ":class:`~matplotlib.patches.Rectangle` which is stored in\n",
    ":attr:`Figure.patch <matplotlib.figure.Figure.patch>`.  As\n",
    "you add subplots (:meth:`~matplotlib.figure.Figure.add_subplot`) and\n",
    "axes (:meth:`~matplotlib.figure.Figure.add_axes`) to the figure\n",
    "these will be appended to the :attr:`Figure.axes\n",
    "<matplotlib.figure.Figure.axes>`.  These are also returned by the\n",
    "methods that create them:\n",
    "\n",
    ".. sourcecode:: ipython\n",
    "\n",
    "    In [156]: fig = plt.figure()\n",
    "\n",
    "    In [157]: ax1 = fig.add_subplot(211)\n",
    "\n",
    "    In [158]: ax2 = fig.add_axes([0.1, 0.1, 0.7, 0.3])\n",
    "\n",
    "    In [159]: ax1\n",
    "    Out[159]: <matplotlib.axes.Subplot instance at 0xd54b26c>\n",
    "\n",
    "    In [160]: print(fig.axes)\n",
    "    [<matplotlib.axes.Subplot instance at 0xd54b26c>,\n",
    "    <matplotlib.axes.Axes instance at 0xd3f0b2c>]\n",
    "\n",
    "Because the figure maintains the concept of the \"current axes\" (see\n",
    ":meth:`Figure.gca <matplotlib.figure.Figure.gca>` and\n",
    ":meth:`Figure.sca <matplotlib.figure.Figure.sca>`) to support the\n",
    "pylab/pyplot state machine, you should not insert or remove axes\n",
    "directly from the axes list, but rather use the\n",
    ":meth:`~matplotlib.figure.Figure.add_subplot` and\n",
    ":meth:`~matplotlib.figure.Figure.add_axes` methods to insert, and the\n",
    ":meth:`~matplotlib.figure.Figure.delaxes` method to delete.  You are\n",
    "free however, to iterate over the list of axes or index into it to get\n",
    "access to ``Axes`` instances you want to customize.  Here is an\n",
    "example which turns all the axes grids on::\n",
    "\n",
    "    for ax in fig.axes:\n",
    "        ax.grid(True)\n",
    "\n",
    "\n",
    "The figure also has its own text, lines, patches and images, which you\n",
    "can use to add primitives directly.  The default coordinate system for\n",
    "the ``Figure`` will simply be in pixels (which is not usually what you\n",
    "want) but you can control this by setting the transform property of\n",
    "the ``Artist`` you are adding to the figure.\n",
    "\n",
    ".. TODO: Is that still true?\n",
    "\n",
    "More useful is \"figure coordinates\" where (0, 0) is the bottom-left of\n",
    "the figure and (1, 1) is the top-right of the figure which you can\n",
    "obtain by setting the ``Artist`` transform to :attr:`fig.transFigure\n",
    "<matplotlib.figure.Figure.transFigure>`:\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import matplotlib.lines as lines\n",
    "\n",
    "fig = plt.figure()\n",
    "\n",
    "l1 = lines.Line2D([0, 1], [0, 1], transform=fig.transFigure, figure=fig)\n",
    "l2 = lines.Line2D([0, 1], [1, 0], transform=fig.transFigure, figure=fig)\n",
    "fig.lines.extend([l1, l2])\n",
    "\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Here is a summary of the Artists the figure contains\n",
    "\n",
    ".. TODO: Add xrefs to this table\n",
    "\n",
    "================ ============================================================\n",
    "Figure attribute Description\n",
    "================ ============================================================\n",
    "axes             A list of Axes instances (includes Subplot)\n",
    "patch            The Rectangle background\n",
    "images           A list of FigureImage patches -\n",
    "                 useful for raw pixel display\n",
    "legends          A list of Figure Legend instances\n",
    "                 (different from Axes.legends)\n",
    "lines            A list of Figure Line2D instances\n",
    "                 (rarely used, see Axes.lines)\n",
    "patches          A list of Figure patches (rarely used, see Axes.patches)\n",
    "texts            A list Figure Text instances\n",
    "================ ============================================================\n",
    "\n",
    "\n",
    "Axes container\n",
    "--------------\n",
    "\n",
    "The :class:`matplotlib.axes.Axes` is the center of the matplotlib\n",
    "universe -- it contains the vast majority of all the ``Artists`` used\n",
    "in a figure with many helper methods to create and add these\n",
    "``Artists`` to itself, as well as helper methods to access and\n",
    "customize the ``Artists`` it contains.  Like the\n",
    ":class:`~matplotlib.figure.Figure`, it contains a\n",
    ":class:`~matplotlib.patches.Patch`\n",
    ":attr:`~matplotlib.axes.Axes.patch` which is a\n",
    ":class:`~matplotlib.patches.Rectangle` for Cartesian coordinates and a\n",
    ":class:`~matplotlib.patches.Circle` for polar coordinates; this patch\n",
    "determines the shape, background and border of the plotting region::\n",
    "\n",
    "    ax = fig.add_subplot(111)\n",
    "    rect = ax.patch  # a Rectangle instance\n",
    "    rect.set_facecolor('green')\n",
    "\n",
    "When you call a plotting method, e.g., the canonical\n",
    ":meth:`~matplotlib.axes.Axes.plot` and pass in arrays or lists of\n",
    "values, the method will create a :meth:`matplotlib.lines.Line2D`\n",
    "instance, update the line with all the ``Line2D`` properties passed as\n",
    "keyword arguments, add the line to the :attr:`Axes.lines\n",
    "<matplotlib.axes.Axes.lines>` container, and returns it to you:\n",
    "\n",
    ".. sourcecode:: ipython\n",
    "\n",
    "    In [213]: x, y = np.random.rand(2, 100)\n",
    "\n",
    "    In [214]: line, = ax.plot(x, y, '-', color='blue', linewidth=2)\n",
    "\n",
    "``plot`` returns a list of lines because you can pass in multiple x, y\n",
    "pairs to plot, and we are unpacking the first element of the length\n",
    "one list into the line variable.  The line has been added to the\n",
    "``Axes.lines`` list:\n",
    "\n",
    ".. sourcecode:: ipython\n",
    "\n",
    "    In [229]: print(ax.lines)\n",
    "    [<matplotlib.lines.Line2D instance at 0xd378b0c>]\n",
    "\n",
    "Similarly, methods that create patches, like\n",
    ":meth:`~matplotlib.axes.Axes.bar` creates a list of rectangles, will\n",
    "add the patches to the :attr:`Axes.patches\n",
    "<matplotlib.axes.Axes.patches>` list:\n",
    "\n",
    ".. sourcecode:: ipython\n",
    "\n",
    "    In [233]: n, bins, rectangles = ax.hist(np.random.randn(1000), 50)\n",
    "\n",
    "    In [234]: rectangles\n",
    "    Out[234]: <a list of 50 Patch objects>\n",
    "\n",
    "    In [235]: print(len(ax.patches))\n",
    "\n",
    "You should not add objects directly to the ``Axes.lines`` or\n",
    "``Axes.patches`` lists unless you know exactly what you are doing,\n",
    "because the ``Axes`` needs to do a few things when it creates and adds\n",
    "an object.  It sets the figure and axes property of the ``Artist``, as\n",
    "well as the default ``Axes`` transformation (unless a transformation\n",
    "is set).  It also inspects the data contained in the ``Artist`` to\n",
    "update the data structures controlling auto-scaling, so that the view\n",
    "limits can be adjusted to contain the plotted data.  You can,\n",
    "nonetheless, create objects yourself and add them directly to the\n",
    "``Axes`` using helper methods like\n",
    ":meth:`~matplotlib.axes.Axes.add_line` and\n",
    ":meth:`~matplotlib.axes.Axes.add_patch`.  Here is an annotated\n",
    "interactive session illustrating what is going on:\n",
    "\n",
    ".. sourcecode:: ipython\n",
    "\n",
    "    In [262]: fig, ax = plt.subplots()\n",
    "\n",
    "    # create a rectangle instance\n",
    "    In [263]: rect = matplotlib.patches.Rectangle((1, 1), width=5, height=12)\n",
    "\n",
    "    # by default the axes instance is None\n",
    "    In [264]: print(rect.axes)\n",
    "    None\n",
    "\n",
    "    # and the transformation instance is set to the \"identity transform\"\n",
    "    In [265]: print(rect.get_transform())\n",
    "    <Affine object at 0x13695544>\n",
    "\n",
    "    # now we add the Rectangle to the Axes\n",
    "    In [266]: ax.add_patch(rect)\n",
    "\n",
    "    # and notice that the ax.add_patch method has set the axes\n",
    "    # instance\n",
    "    In [267]: print(rect.axes)\n",
    "    Axes(0.125,0.1;0.775x0.8)\n",
    "\n",
    "    # and the transformation has been set too\n",
    "    In [268]: print(rect.get_transform())\n",
    "    <Affine object at 0x15009ca4>\n",
    "\n",
    "    # the default axes transformation is ax.transData\n",
    "    In [269]: print(ax.transData)\n",
    "    <Affine object at 0x15009ca4>\n",
    "\n",
    "    # notice that the xlimits of the Axes have not been changed\n",
    "    In [270]: print(ax.get_xlim())\n",
    "    (0.0, 1.0)\n",
    "\n",
    "    # but the data limits have been updated to encompass the rectangle\n",
    "    In [271]: print(ax.dataLim.bounds)\n",
    "    (1.0, 1.0, 5.0, 12.0)\n",
    "\n",
    "    # we can manually invoke the auto-scaling machinery\n",
    "    In [272]: ax.autoscale_view()\n",
    "\n",
    "    # and now the xlim are updated to encompass the rectangle\n",
    "    In [273]: print(ax.get_xlim())\n",
    "    (1.0, 6.0)\n",
    "\n",
    "    # we have to manually force a figure draw\n",
    "    In [274]: ax.figure.canvas.draw()\n",
    "\n",
    "\n",
    "There are many, many ``Axes`` helper methods for creating primitive\n",
    "``Artists`` and adding them to their respective containers.  The table\n",
    "below summarizes a small sampling of them, the kinds of ``Artist`` they\n",
    "create, and where they store them\n",
    "\n",
    "==============================  ====================  =======================\n",
    "Helper method                   Artist                Container\n",
    "==============================  ====================  =======================\n",
    "ax.annotate - text annotations  Annotate              ax.texts\n",
    "ax.bar  - bar charts            Rectangle             ax.patches\n",
    "ax.errorbar - error bar plots   Line2D and Rectangle  ax.lines and ax.patches\n",
    "ax.fill - shared area           Polygon               ax.patches\n",
    "ax.hist - histograms            Rectangle             ax.patches\n",
    "ax.imshow - image data          AxesImage             ax.images\n",
    "ax.legend - axes legends        Legend                ax.legends\n",
    "ax.plot - xy plots              Line2D                ax.lines\n",
    "ax.scatter - scatter charts     PolygonCollection     ax.collections\n",
    "ax.text - text                  Text                  ax.texts\n",
    "==============================  ====================  =======================\n",
    "\n",
    "\n",
    "In addition to all of these ``Artists``, the ``Axes`` contains two\n",
    "important ``Artist`` containers: the :class:`~matplotlib.axis.XAxis`\n",
    "and :class:`~matplotlib.axis.YAxis`, which handle the drawing of the\n",
    "ticks and labels.  These are stored as instance variables\n",
    ":attr:`~matplotlib.axes.Axes.xaxis` and\n",
    ":attr:`~matplotlib.axes.Axes.yaxis`.  The ``XAxis`` and ``YAxis``\n",
    "containers will be detailed below, but note that the ``Axes`` contains\n",
    "many helper methods which forward calls on to the\n",
    ":class:`~matplotlib.axis.Axis` instances so you often do not need to\n",
    "work with them directly unless you want to.  For example, you can set\n",
    "the font color of the ``XAxis`` ticklabels using the ``Axes`` helper\n",
    "method::\n",
    "\n",
    "    for label in ax.get_xticklabels():\n",
    "        label.set_color('orange')\n",
    "\n",
    "Below is a summary of the Artists that the Axes contains\n",
    "\n",
    "==============    ======================================\n",
    "Axes attribute    Description\n",
    "==============    ======================================\n",
    "artists           A list of Artist instances\n",
    "patch             Rectangle instance for Axes background\n",
    "collections       A list of Collection instances\n",
    "images            A list of AxesImage\n",
    "legends           A list of Legend instances\n",
    "lines             A list of Line2D instances\n",
    "patches           A list of Patch instances\n",
    "texts             A list of Text instances\n",
    "xaxis             matplotlib.axis.XAxis instance\n",
    "yaxis             matplotlib.axis.YAxis instance\n",
    "==============    ======================================\n",
    "\n",
    "\n",
    "Axis containers\n",
    "---------------\n",
    "\n",
    "The :class:`matplotlib.axis.Axis` instances handle the drawing of the\n",
    "tick lines, the grid lines, the tick labels and the axis label.  You\n",
    "can configure the left and right ticks separately for the y-axis, and\n",
    "the upper and lower ticks separately for the x-axis.  The ``Axis``\n",
    "also stores the data and view intervals used in auto-scaling, panning\n",
    "and zooming, as well as the :class:`~matplotlib.ticker.Locator` and\n",
    ":class:`~matplotlib.ticker.Formatter` instances which control where\n",
    "the ticks are placed and how they are represented as strings.\n",
    "\n",
    "Each ``Axis`` object contains a :attr:`~matplotlib.axis.Axis.label` attribute\n",
    "(this is what :mod:`.pyplot` modifies in calls to `~.pyplot.xlabel` and\n",
    "`~.pyplot.ylabel`) as well as a list of major and minor ticks.  The ticks are\n",
    "`.axis.XTick` and `.axis.YTick` instances, which contain the actual line and\n",
    "text primitives that render the ticks and ticklabels.  Because the ticks are\n",
    "dynamically created as needed (e.g., when panning and zooming), you should\n",
    "access the lists of major and minor ticks through their accessor methods\n",
    "`.axis.Axis.get_major_ticks` and `.axis.Axis.get_minor_ticks`.  Although\n",
    "the ticks contain all the primitives and will be covered below, ``Axis``\n",
    "instances have accessor methods that return the tick lines, tick labels, tick\n",
    "locations etc.:\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "fig, ax = plt.subplots()\n",
    "axis = ax.xaxis\n",
    "axis.get_ticklocs()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "axis.get_ticklabels()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "note there are twice as many ticklines as labels because by default there are\n",
    "tick lines at the top and bottom but only tick labels below the xaxis;\n",
    "however, this can be customized.\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "axis.get_ticklines()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "And with the above methods, you only get lists of major ticks back by\n",
    "default, but you can also ask for the minor ticks:\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "axis.get_ticklabels(minor=True)\n",
    "axis.get_ticklines(minor=True)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Here is a summary of some of the useful accessor methods of the ``Axis``\n",
    "(these have corresponding setters where useful, such as\n",
    ":meth:`~matplotlib.axis.Axis.set_major_formatter`.)\n",
    "\n",
    "====================  =====================================================\n",
    "Accessor method       Description\n",
    "====================  =====================================================\n",
    "get_scale             The scale of the axis, e.g., 'log' or 'linear'\n",
    "get_view_interval     The interval instance of the axis view limits\n",
    "get_data_interval     The interval instance of the axis data limits\n",
    "get_gridlines         A list of grid lines for the Axis\n",
    "get_label             The axis label - a Text instance\n",
    "get_ticklabels        A list of Text instances - keyword minor=True|False\n",
    "get_ticklines         A list of Line2D instances - keyword minor=True|False\n",
    "get_ticklocs          A list of Tick locations - keyword minor=True|False\n",
    "get_major_locator     The `.ticker.Locator` instance for major ticks\n",
    "get_major_formatter   The `.ticker.Formatter` instance for major ticks\n",
    "get_minor_locator     The `.ticker.Locator` instance for minor ticks\n",
    "get_minor_formatter   The `.ticker.Formatter` instance for minor ticks\n",
    "get_major_ticks       A list of Tick instances for major ticks\n",
    "get_minor_ticks       A list of Tick instances for minor ticks\n",
    "grid                  Turn the grid on or off for the major or minor ticks\n",
    "====================  =====================================================\n",
    "\n",
    "Here is an example, not recommended for its beauty, which customizes\n",
    "the axes and tick properties\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plt.figure creates a matplotlib.figure.Figure instance\n",
    "fig = plt.figure()\n",
    "rect = fig.patch  # a rectangle instance\n",
    "rect.set_facecolor('lightgoldenrodyellow')\n",
    "\n",
    "ax1 = fig.add_axes([0.1, 0.3, 0.4, 0.4])\n",
    "rect = ax1.patch\n",
    "rect.set_facecolor('lightslategray')\n",
    "\n",
    "\n",
    "for label in ax1.xaxis.get_ticklabels():\n",
    "    # label is a Text instance\n",
    "    label.set_color('red')\n",
    "    label.set_rotation(45)\n",
    "    label.set_fontsize(16)\n",
    "\n",
    "for line in ax1.yaxis.get_ticklines():\n",
    "    # line is a Line2D instance\n",
    "    line.set_color('green')\n",
    "    line.set_markersize(25)\n",
    "    line.set_markeredgewidth(3)\n",
    "\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "\n",
    "Tick containers\n",
    "---------------\n",
    "\n",
    "The :class:`matplotlib.axis.Tick` is the final container object in our\n",
    "descent from the :class:`~matplotlib.figure.Figure` to the\n",
    ":class:`~matplotlib.axes.Axes` to the :class:`~matplotlib.axis.Axis`\n",
    "to the :class:`~matplotlib.axis.Tick`.  The ``Tick`` contains the tick\n",
    "and grid line instances, as well as the label instances for the upper\n",
    "and lower ticks.  Each of these is accessible directly as an attribute\n",
    "of the ``Tick``.\n",
    "\n",
    "==============   ==========================================================\n",
    "Tick attribute   Description\n",
    "==============   ==========================================================\n",
    "tick1line        Line2D instance\n",
    "tick2line        Line2D instance\n",
    "gridline         Line2D instance\n",
    "label1           Text instance\n",
    "label2           Text instance\n",
    "==============   ==========================================================\n",
    "\n",
    "Here is an example which sets the formatter for the right side ticks with\n",
    "dollar signs and colors them green on the right side of the yaxis.\n",
    "\n",
    "\n",
    ".. include:: ../../gallery/pyplots/dollar_ticks.rst\n",
    "   :start-after: y axis labels.\n",
    "   :end-before: -------\n",
    "\n"
   ]
  }
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