Note
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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 matplotlib.pyplot as plt
import numpy as np
import matplotlib.lines as lines
import matplotlib.text as mtext
import matplotlib.transforms as mtransforms
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)
# Override the axes property setter to set Axes on our children as well.
@lines.Line2D.axes.setter
def axes(self, new_axes):
self.text.axes = new_axes
lines.Line2D.axes.fset(self, new_axes) # Call the superclass property setter.
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()
References
The use of the following functions, methods, classes and modules is shown in this example: