>>> """
=======================
Artist within an artist
=======================

Override basic methods so an artist can contain another
artist.  In this case, the line contains a Text instance to label it.
"""
... import numpy as np
... import matplotlib.pyplot as plt
... import matplotlib.lines as lines
... import matplotlib.transforms as mtransforms
... import matplotlib.text as mtext
... 
... 
... class MyLine(lines.Line2D):
...     def __init__(self, *args, **kwargs):
...         # we'll update the position when the line data is set
...         self.text = mtext.Text(0, 0, '')
...         super().__init__(*args, **kwargs)
... 
...         # we can't access the label attr until *after* the line is
...         # initiated
...         self.text.set_text(self.get_label())
... 
...     def set_figure(self, figure):
...         self.text.set_figure(figure)
...         super().set_figure(figure)
... 
...     def set_axes(self, axes):
...         self.text.set_axes(axes)
...         super().set_axes(axes)
... 
...     def set_transform(self, transform):
...         # 2 pixel offset
...         texttrans = transform + mtransforms.Affine2D().translate(2, 2)
...         self.text.set_transform(texttrans)
...         super().set_transform(transform)
... 
...     def set_data(self, x, y):
...         if len(x):
...             self.text.set_position((x[-1], y[-1]))
... 
...         super().set_data(x, y)
... 
...     def draw(self, renderer):
...         # draw my label at the end of the line with 2 pixel offset
...         super().draw(renderer)
...         self.text.draw(renderer)
... 
... # Fixing random state for reproducibility
... np.random.seed(19680801)
... 
... 
... fig, ax = plt.subplots()
... x, y = np.random.rand(2, 20)
... line = MyLine(x, y, mfc='red', ms=12, label='line label')
... line.text.set_color('red')
... line.text.set_fontsize(16)
... 
... ax.add_line(line)
... 
... plt.show()
... 
... #############################################################################
... #
... # .. admonition:: References
... #
... #    The use of the following functions, methods, classes and modules is shown
... #    in this example:
... #
... #    - `matplotlib.lines`
... #    - `matplotlib.lines.Line2D`
... #    - `matplotlib.lines.Line2D.set_data`
... #    - `matplotlib.artist`
... #    - `matplotlib.artist.Artist`
... #    - `matplotlib.artist.Artist.draw`
... #    - `matplotlib.artist.Artist.set_transform`
... #    - `matplotlib.text`
... #    - `matplotlib.text.Text`
... #    - `matplotlib.text.Text.set_color`
... #    - `matplotlib.text.Text.set_fontsize`
... #    - `matplotlib.text.Text.set_position`
... #    - `matplotlib.axes.Axes.add_line`
... #    - `matplotlib.transforms`
... #    - `matplotlib.transforms.Affine2D`
...