import matplotlib.pyplot as plt
from matplotlib.text import OffsetFrom
fig, ax = plt.subplots(figsize=(3, 2))
an1 = ax.annotate("Test 1", xy=(0.5, 0.5), xycoords="data",
va="center", ha="center",
bbox=dict(boxstyle="round", fc="w"))
offset_from = OffsetFrom(an1, (0.5, 0))
an2 = ax.annotate("Test 2", xy=(0.1, 0.1), xycoords="data",
xytext=(0, -10), textcoords=offset_from,
# xytext is offset points from "xy=(0.5, 0), xycoords=an1"
va="top", ha="center",
bbox=dict(boxstyle="round", fc="w"),
arrowprops=dict(arrowstyle="->"))
plt.show()