Is it possible to anchor a matplotlib annotation to a data coordinate in the x-axis, but to a relative location in the y-axis?

Question

I have a plot where I\'d like to annotate a specific location on the x-axis with an arrow and a label:

• The location of the tip of the arrow needs to be specifi

Answer 1

Pass the transformation to the xycoords and textcoords parameters instead of to the transform parameter. Like so:

fig, ax = make_example_plot()
tform = blended_transform_factory(ax.transData, ax.transAxes)
ax.annotate(label, xy=(r, 0), xycoords=tform, 
            xytext=(r, 0.9), textcoords=tform, fontsize='xx-large',
            ha='center', va='center', color='r', arrowprops=arrowprops)