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# Anchored Artists

    from matplotlib.patches import Rectangle, Ellipse

    from matplotlib.offsetbox import AnchoredOffsetbox, AuxTransformBox, VPacker,\
        TextArea, DrawingArea

    class AnchoredText(AnchoredOffsetbox):
        def __init__(self, s, loc, pad=0.4, borderpad=0.5, prop=None, frameon=True):

            self.txt = TextArea(s,
                                minimumdescent=False)

            super(AnchoredText, self).__init__(loc, pad=pad, borderpad=borderpad,
                                               child=self.txt,
                                               prop=prop,
                                               frameon=frameon)

    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 give 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(Rectangle((0, 0), size, 0, fc="none", lw=1.0))

            self.txt_label = TextArea(label, minimumdescent=False)

            self._box = VPacker(children=[self.size_bar, self.txt_label],
                                align="center",
                                pad=0, sep=sep)

            AnchoredOffsetbox.__init__(self, loc, pad=pad, borderpad=borderpad,
                                       child=self._box,
                                       prop=prop,
                                       frameon=frameon)

    class AnchoredEllipse(AnchoredOffsetbox):
        def __init__(self, transform, width, height, angle, loc,
                     pad=0.1, borderpad=0.1, prop=None, frameon=True):
            """
            Draw an ellipse the size in data coordinate of the give axes.

            pad, borderpad in fraction of the legend font size (or prop)
            """
            self._box = AuxTransformBox(transform)
            self.ellipse = Ellipse((0, 0), width, height, angle)
            self._box.add_artist(self.ellipse)

            AnchoredOffsetbox.__init__(self, loc, pad=pad, borderpad=borderpad,
                                       child=self._box,
                                       prop=prop,
                                       frameon=frameon)

    class AnchoredDrawingArea(AnchoredOffsetbox):
        def __init__(self, width, height, xdescent, ydescent,
                     loc, pad=0.4, borderpad=0.5, prop=None, frameon=True):

            self.da = DrawingArea(width, height, xdescent, ydescent)

            super(AnchoredDrawingArea, self).__init__(loc, pad=pad, borderpad=borderpad,
                                                      child=self.da,
                                                      prop=None,
                                                      frameon=frameon)

    if __name__ == "__main__":

        import matplotlib.pyplot as plt

        ax = plt.gca()
        ax.set_aspect(1.)

        at = AnchoredText("Figure 1a",
                          loc=2, frameon=True)
        at.patch.set_boxstyle("round,pad=0.,rounding_size=0.2")
        ax.add_artist(at)

        from matplotlib.patches import Circle
        ada = AnchoredDrawingArea(20, 20, 0, 0,
                                  loc=1, pad=0., frameon=False)
        p = Circle((10, 10), 10)
        ada.da.add_artist(p)
        ax.add_artist(ada)

        # draw an ellipse of width=0.1, height=0.15 in the data coordinate
        ae = AnchoredEllipse(ax.transData, width=0.1, height=0.15, angle=0.,
                             loc=3, pad=0.5, borderpad=0.4, frameon=True)

        ax.add_artist(ae)

        # draw a horizontal bar with length of 0.1 in Data coordinate
        # (ax.transData) with a label underneath.
        asb = AnchoredSizeBar(ax.transData,
                              0.1,
                              r"1$^{\prime}$",
                              loc=8,
                              pad=0.1, borderpad=0.5, sep=5,
                              frameon=False)
        ax.add_artist(asb)

        plt.draw()
        plt.show()

Total running time of the script: ( 0 minutes 0.139 seconds)

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