matplotlib: alignment of legend title

Question

In matplotlib, how can I adjust the alignment of the legend title? It is always centered, but I need it to be left aligned with the legend box. I tried to change the alignment of the title's Text artist which has no effect. See the following example for details:

from pylab import *  x = linspace(0, 1) plot(x, x, label="1") plot(x, x**2, label="2") plot(x, x**3, label="3") plot(x, sqrt(x), label="square root")  l = legend(title="Title", loc="best") l.get_title().set_ha("left")               # <== does not work  show() 

The question boils down to what and who controls the anchor point of the title alignment? Changing the alignment to "right" or "center" has a noticeable effect. Second observation: for long title strings the anchor point moves to the left border of the legend box ...

Answer 1

You may align the complete legend box setting leg._legend_box.align. This aligns everything inside the legend box, but the effect is the desired one to have the title on either side of the box instead of the center.

• Left aligned

  leg = plt.legend(title="Title") leg._legend_box.align = "left" 

  

• Right aligned

  leg = plt.legend(title="Title") leg._legend_box.align = "right" 

  

Answer 2

I think you need to displace the Text object, using the set_position((x, y)) method. The units of x and y are pixels, so you'll have to experiment with what values look right, or use a Transform. I'm not sure off hand which combination of Transforms might be most useful.

So in short, something like this might work:

l.get_title().set_position((-10, 0)) # -10 is a guess