Text alignment in a Matplotlib legend

问题:

I am trying to right-align the entries in a matplotlib axes legend (by default they are left-aligned), but can't seem to find any way of doing this. The setup I have is below:

(I have added data and labels to my_fig axes using the ax.plot() command)

ax = my_fig.get_axes()[0]
legend_font = FontProperties(size=10)
ax.legend(prop=legend_font, num_points=1, markerscale=0.5)

There is a list of legend keyword arguments in the docs for matplotlib Axes, but there doesn't seem to be any straighforward way to set the alignment of the legend entries there. Anybody know of a backdoor way of doing this? Thanks.

EDIT:

To clarify what I am trying to achieve, right now my legend looks like:

Maneuver: 12-OCT-2011 12:00 UTC 

Bias: 14-OCT-2011 06:00 UTC

I want it to look like:

Maneuver: 12-OCT-2011 12:00 UTC 

    Bias: 14-OCT-2011 06:00 UTC

回答1:

The backdoor you're looking for is the following:

# get the width of your widest label, since every label will need 
# to shift by this amount after we align to the right
shift = max([t.get_window_extent().width for t in legend.get_texts()])
for t in legend.get_texts():
    t.set_ha('right') # ha is alias for horizontalalignment
    t.set_position((shift,0))

回答2:

I tried to get the example work, but I couldn't.

At least since matplotlib version 1.1.1 (maybe earlier) we need a dedicated renderer instance. Take care of your backend which defines the renderer. Depending on backend the output may look fine on screen but dismal as PDF.

# get the width of your widest label, since every label will need 
#to shift by this amount after we align to the right
renderer = figure.canvas.get_renderer()
shift = max([t.get_window_extent(renderer).width for t in legend.get_texts()])
for t in legend.get_texts():
    t.set_ha('right') # ha is alias for horizontalalignment
    t.set_position((shift,0))