MPL multicolor text

from pylab import figure, show

from matplotlib.offsetbox import AnchoredOffsetbox, HPacker, TextArea


f = figure(1)
ax = f.add_subplot(111)

txt1 = TextArea("A$^3$", textprops=dict(color="r", size=150))
txt2 = TextArea("gb", textprops=dict(color="k", size=150))

txt = HPacker(children=[txt1, txt2],
            align="baseline",
            pad=0, sep=0)

def txt_offset(*kl):
  return ax.transData.transform_point((0.2, 0.2))
txt.set_offset(txt_offset)

# box = AnchoredOffsetbox(loc=3, pad=0, borderpad=0,
#                         bbox_to_anchor=(0.5, 0.5),
#                         bbox_transform=ax.transData,
#                         child=txt,
#                         frameon=False)

ax.add_artist(txt)

show()