[Python] Automatic placement of a text box? ie empty legend [matplotlib]

I still need help with this.

I'd like to have the Sample A box place itself in the optimal empty space, so as not to overly any graphing elements (if possible):



import numpy.random
import matplotlib.pyplot as plt

fig = plt.figure(1, figsize=(5,5))
fig.clf()

ax = fig.add_subplot(111)
ax.set_aspect(1)

x1 = -1 + numpy.random.randn(100)
y1 = -1 + numpy.random.randn(100)
x2 = 1. + numpy.random.randn(100)
y2 = 1. + numpy.random.randn(100)

ax.scatter(x1, y1, color="r")
ax.scatter(x2, y2, color="g")

bbox_props = dict(boxstyle="round", fc="w", ec="0.5", alpha=0.9)
ax.text(-2, -2, "Sample A", ha="center", va="center", size ,
bbox»ox_props)

plt.draw()
plt.show()

A simple alternative might be to place the label
just outside of the plot region either at the top
or the bottom of the plot instead of finding
an open area in which to place the label ....

def extremes( x1 , y1 , x2 , y2 ) :

min_x1 = min( x1 )
min_y1 = min( y1 )

max_x1 = max( x1 )
max_y1 = max( y1 )

min_x2 = min( x2 )
min_y2 = min( y2 )

max_x2 = max( x2 )
max_y2 = max( y2 )

min_x = min( min_x1 , min_x2 )
min_y = min( min_y1 , min_y2 )

max_x = max( max_x1 , max_x2 )
max_y = max( max_y1 , max_y2 )

aminx = min_x
aminy = min_y - 1.4

amaxx = max_x
amaxy = max_y + 1.4

return aminx , aminy , amaxx , amaxy


# bump up the plot size a bit

fig = plt.figure( 1 , figsize = ( 6 , 6 ) )

....

aminx , aminy , amaxx , amaxy = extremes( x1 , y1 , x2 , y2 )

....

# label at top center

ax.text( 0 , amaxy , "Sample A" , ha = "center" , va = "center" ,
size = 16 , bbox = bbox_props )