.. _users_artists: Introduction to Artists ----------------------- Almost all objects you interact with on a Matplotlib plot are called "Artist" (and are subclasses of the `.Artist` class). :doc:`Figure <../figure/index>` and :doc:`Axes <../axes/index>` are Artists, and generally contain `~.axis.Axis` Artists and Artists that contain data or annotation information. Creating Artists ~~~~~~~~~~~~~~~~ Usually we do not instantiate Artists directly, but rather use a plotting method on `~.axes.Axes`. Some examples of plotting methods and the Artist object they create is given below: ========================================= ================= Axes helper method Artist ========================================= ================= `~.axes.Axes.annotate` - text annotations `.Annotation` `~.axes.Axes.bar` - bar charts `.Rectangle` `~.axes.Axes.errorbar` - error bar plots `.Line2D` and `.Rectangle` `~.axes.Axes.fill` - shared area `.Polygon` `~.axes.Axes.hist` - histograms `.Rectangle` `~.axes.Axes.imshow` - image data `.AxesImage` `~.axes.Axes.legend` - Axes legend `.Legend` `~.axes.Axes.plot` - xy plots `.Line2D` `~.axes.Axes.scatter` - scatter charts `.PolyCollection` `~.axes.Axes.text` - text `.Text` ========================================= ================= As an example, we can save the Line2D Artist returned from `.axes.Axes.plot`: .. sourcecode:: ipython In [209]: import matplotlib.pyplot as plt In [210]: import matplotlib.artist as martist In [211]: import numpy as np In [212]: fig, ax = plt.subplots() In [213]: x, y = np.random.rand(2, 100) In [214]: lines = ax.plot(x, y, '-', label='example') In [215]: print(lines) [] Note that ``plot`` returns a _list_ of lines because you can pass in multiple x, y pairs to plot. The line has been added to the Axes, and we can retrieve the Artist via `~.Axes.get_lines()`: .. sourcecode:: ipython In [216]: print(ax.get_lines()) In [217]: print(ax.get_lines()[0]) Line2D(example) Changing Artist properties ~~~~~~~~~~~~~~~~~~~~~~~~~~ Getting the ``lines`` object gives us access to all the properties of the Line2D object. So if we want to change the *linewidth* after the fact, we can do so using `.Artist.set`. .. plot:: :include-source: fig, ax = plt.subplots(figsize=(4, 2.5)) x = np.arange(0, 13, 0.2) y = np.sin(x) lines = ax.plot(x, y, '-', label='example', linewidth=0.2, color='blue') lines[0].set(color='green', linewidth=2) We can interrogate the full list of settable properties with `matplotlib.artist.getp`: .. sourcecode:: ipython In [218]: martist.getp(lines[0]) agg_filter = None alpha = None animated = False antialiased or aa = True bbox = Bbox(x0=0.004013842290585101, y0=0.013914221641967... children = [] clip_box = TransformedBbox( Bbox(x0=0.0, y0=0.0, x1=1.0, ... clip_on = True clip_path = None color or c = blue dash_capstyle = butt dash_joinstyle = round data = (array([0.91377845, 0.58456834, 0.36492019, 0.0379... drawstyle or ds = default figure = Figure(550x450) fillstyle = full gapcolor = None gid = None in_layout = True label = example linestyle or ls = - linewidth or lw = 2.0 marker = None markeredgecolor or mec = blue markeredgewidth or mew = 1.0 markerfacecolor or mfc = blue markerfacecoloralt or mfcalt = none markersize or ms = 6.0 markevery = None mouseover = False path = Path(array([[0.91377845, 0.51224793], [0.58... path_effects = [] picker = None pickradius = 5 rasterized = False sketch_params = None snap = None solid_capstyle = projecting solid_joinstyle = round tightbbox = Bbox(x0=70.4609002763619, y0=54.321277798941786, x... transform = CompositeGenericTransform( TransformWrapper( ... transformed_clip_path_and_affine = (None, None) url = None visible = True window_extent = Bbox(x0=70.4609002763619, y0=54.321277798941786, x... xdata = [0.91377845 0.58456834 0.36492019 0.03796664 0.884... xydata = [[0.91377845 0.51224793] [0.58456834 0.9820474 ] ... ydata = [0.51224793 0.9820474 0.24469912 0.61647032 0.483... zorder = 2 Note most Artists also have a distinct list of setters; e.g. `.Line2D.set_color` or `.Line2D.set_linewidth`. Changing Artist data ~~~~~~~~~~~~~~~~~~~~ In addition to styling properties like *color* and *linewidth*, the Line2D object has a *data* property. You can set the data after the line has been created using `.Line2D.set_data`. This is often used for Animations, where the same line is shown evolving over time (see :doc:`../animations/index`) .. plot:: :include-source: fig, ax = plt.subplots(figsize=(4, 2.5)) x = np.arange(0, 13, 0.2) y = np.sin(x) lines = ax.plot(x, y, '-', label='example') lines[0].set_data([x, np.cos(x)]) Manually adding Artists ~~~~~~~~~~~~~~~~~~~~~~~ Not all Artists have helper methods, or you may want to use a low-level method for some reason. For example the `.patches.Circle` Artist does not have a helper, but we can still create and add to an Axes using the `.axes.Axes.add_artist` method: .. plot:: :include-source: import matplotlib.patches as mpatches fig, ax = plt.subplots(figsize=(4, 2.5)) circle = mpatches.Circle((0.5, 0.5), 0.25, ec="none") ax.add_artist(circle) clipped_circle = mpatches.Circle((1, 0.5), 0.125, ec="none", facecolor='C1') ax.add_artist(clipped_circle) ax.set_aspect(1) The Circle takes the center and radius of the Circle as arguments to its constructor; optional arguments are passed as keyword arguments. Note that when we add an Artist manually like this, it doesn't necessarily adjust the axis limits like most of the helper methods do, so the Artists can be clipped, as is the case above for the ``clipped_circle`` patch. See :ref:`artist_reference` for other patches. Removing Artists ~~~~~~~~~~~~~~~~ Sometimes we want to remove an Artist from a figure without re-specifying the whole figure from scratch. Most Artists have a usable *remove* method that will remove the Artist from its Axes list. For instance ``lines[0].remove()`` would remove the *Line2D* artist created in the example above.