Get Seaborn legend location - python-3.x

Question

I want to add comments under my legend. Here is a sample code doing what I want:
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
np.random.seed(0)
df1 = pd.DataFrame(np.random.normal(size=100))
df2 = pd.DataFrame(np.random.uniform(size=100))
fig,ax=plt.subplots()
sns.distplot(df1,ax=ax,label='foo')
sns.distplot(df2,ax=ax,label='bar')
hardlocy = 0.92
xmargin=0.02
xmin,xmax = ax.get_xlim()
xtxt=xmax-(xmax-xmin)*xmargin
leg = ax.legend()
plt.text(xtxt,hardlocy,"Comment",
horizontalalignment='right'
);
Result is:
As you can see, I rely on manual position setting, at least for y-axis. I would like to do it automatically.
As per this thread and this one, I have tried to access legend characteristics through p = leg.get_window_extent(), but I have obtain the following error message:
AttributeError: 'NoneType' object has no attribute 'points_to_pixels'
(which is very similar to this closed issue)
I run MacOS Catalina version 10.15.4 and I have performed a successful conda update --all a few minutes ago, without any result.
How can I automatically place my comments?

Answer 1

Thanks to #JohanC, from this question:
One needs to draw a figure for its legend to be worked out. Therefore, a working code here could be:
np.random.seed(0)
df1 = pd.DataFrame(np.random.normal(size=100))
df2 = pd.DataFrame(np.random.uniform(size=100))
fig,ax=plt.subplots()
sns.distplot(df1,ax=ax,label='foo')
sns.distplot(df2,ax=ax,label='bar')
ymargin=0.05
leg = ax.legend()
fig.canvas.draw()
bbox = leg.get_window_extent()
inv = ax.transData.inverted()
(xloc,yloc)=inv.transform((bbox.x1,bbox.y0))
ymin,ymax = ax.get_ylim()
yloc_margin=yloc-(ymax-ymin)*ymargin
ax.text(xloc,yloc_margin,"Comment",horizontalalignment='right')