from matplotlib.patches import ConnectionPatch
%matplotlib inline

t = np.arange(10)
np.random.seed(99)
y1 = np.insert(np.cumsum(sp.stats.norm.rvs(size=9)), 0, 0)
y2 = np.insert(np.cumsum(sp.stats.norm.rvs(size=9)), 0, 0)
y3 = np.insert(np.cumsum(sp.stats.norm.rvs(size=9)), 0, 0)
y4 = np.insert(np.cumsum(sp.stats.norm.rvs(size=9)), 0, 0)

ax1 = plt.subplot(4, 1, 1)
ax1.plot(t, y1, '-o')
ax1.set_xticklabels([])
ax1.set_yticklabels([])
ax1.set_ylim(-9, 9)
ax1.set_zorder(2)
ax1.set_ylabel("sample 1").set_rotation(0)
ax1.yaxis.set_tick_params(pad=30)

plt.title("sample of Random process")

ax2 = plt.subplot(4, 1, 2)
ax2.plot(t, y2, '-o')
ax2.set_xticklabels([])
ax2.set_yticklabels([])
ax2.set_ylim(-9, 9)
ax2.set_zorder(1)
ax2.set_ylabel("sample 2").set_rotation(0)
ax2.yaxis.set_tick_params(pad=30)

ax3 = plt.subplot(4, 1, 3)
ax3.plot(t, y3, '-o')
ax3.set_xticklabels([])
ax3.set_yticklabels([])
ax3.set_ylim(-9, 9)
ax3.set_zorder(1)
ax3.set_ylabel("sample 3").set_rotation(0)
ax3.yaxis.set_tick_params(pad=30)

ax4 = plt.subplot(4, 1, 4)
ax4.plot(t, y4, '-o')
ax4.set_yticklabels([])
ax4.set_ylim(-9, 9)
ax4.set_zorder(1)
ax4.set_ylabel("sample 4").set_rotation(0)
ax4.yaxis.set_tick_params(pad=30)
ax4.annotate('$Y_6$', xy=(5.92, -19), xycoords='data', annotation_clip=False)

con = ConnectionPatch(xyA=(6, 9), xyB=(6, -9), ls="--", lw=2, color="gray",
                      coordsA="data", coordsB="data", axesA=ax1, axesB=ax4)
ax1.add_artist(con)

plt.show()