Verankerte Künstler

Dieses Beispiel veranschaulicht die Verwendung der verankerten Objekte ohne die in mpl_toolkits.axes_grid1. Diese Version der Abbildung ähnelt der in Simple Anchored Artists , wird jedoch nur mit dem Namensraum matplotlib ohne die Hilfe zusätzlicher Toolkits implementiert.

from matplotlib import pyplot as plt
from matplotlib.lines import Line2D
from matplotlib.patches import Circle, Ellipse
from matplotlib.offsetbox import (
    AnchoredOffsetbox, AuxTransformBox, DrawingArea, TextArea, VPacker)


def draw_text(ax):
    """Draw a text-box anchored to the upper-left corner of the figure."""
    box = AnchoredOffsetbox(child=TextArea("Figure 1a"),
                            loc="upper left", frameon=True)
    box.patch.set_boxstyle("round,pad=0.,rounding_size=0.2")
    ax.add_artist(box)


def draw_circles(ax):
    """Draw circles in axes coordinates."""
    area = DrawingArea(40, 20, 0, 0)
    area.add_artist(Circle((10, 10), 10, fc="tab:blue"))
    area.add_artist(Circle((30, 10), 5, fc="tab:red"))
    box = AnchoredOffsetbox(
        child=area, loc="upper right", pad=0, frameon=False)
    ax.add_artist(box)


def draw_ellipse(ax):
    """Draw an ellipse of width=0.1, height=0.15 in data coordinates."""
    aux_tr_box = AuxTransformBox(ax.transData)
    aux_tr_box.add_artist(Ellipse((0, 0), width=0.1, height=0.15))
    box = AnchoredOffsetbox(child=aux_tr_box, loc="lower left", frameon=True)
    ax.add_artist(box)


class AnchoredSizeBar(AnchoredOffsetbox):
    def __init__(self, transform, size, label, loc,
                 pad=0.1, borderpad=0.1, sep=2, prop=None, frameon=True):
        """
        Draw a horizontal bar with the size in data coordinate of the given
        axes. A label will be drawn underneath (center-aligned).

        pad, borderpad in fraction of the legend font size (or prop)
        sep in points.
        """
        self.size_bar = AuxTransformBox(transform)
        self.size_bar.add_artist(Line2D([0, size], [0, 0], color="black"))
        self.txt_label = TextArea(label)
        self._box = VPacker(children=[self.size_bar, self.txt_label],
                            align="center",
                            pad=0, sep=sep)
        super().__init__(loc, pad=pad, borderpad=borderpad,
                         child=self._box, prop=prop, frameon=frameon)


def draw_sizebar(ax):
    """
    Draw a horizontal bar with length of 0.1 in data coordinates,
    with a fixed label underneath.
    """
    asb = AnchoredSizeBar(ax.transData,
                          0.1,
                          r"1$^{\prime}$",
                          loc='lower center',
                          pad=0.1, borderpad=0.5, sep=5,
                          frameon=False)
    ax.add_artist(asb)


fig, ax = plt.subplots()
ax.set_aspect(1)

draw_text(ax)
draw_circles(ax)
draw_ellipse(ax)
draw_sizebar(ax)

plt.show()