python - Fill the right column of a matplotlib legend first

Question

Hey I am trying to fit a legend onto a plot so that it doesn't obscure the graph.

import numpy as np
import matplotlib.pyplot as plt

X = np.linspace(0,100,11)

plt.plot(X,-X, label='plot 1')
plt.plot(X,-2*X, label='plot 2')
plt.plot(X,-3*X, label='plot 3')

leg=plt.legend(ncol=2)
leg.get_frame().set_visible(False)

plt.show()

So in the minimum working example, above, what I want to be able to do is move the 'plot 2' label in the legend into the right column, i.e. directly under 'plot 3'.

Any help would be appreciated, thanks.

Answer 1

A diffrerent implementation of @cosmosis answer. It's probably more flexible.

import numpy as np
import matplotlib.pyplot as plt

X = np.linspace(0,100,11)

plt.plot(X,-X, label='plot 1', color='red')
plt.plot(X,-2*X, label='plot 2', color='green')
plt.plot(X,-3*X, label='plot 3', color='blue')

(lines, labels) = plt.gca().get_legend_handles_labels()
#it's safer to use linestyle='none' and marker='none' that setting the color to white
#should be invisible whatever is the background
lines.insert(1, plt.Line2D(X,X, linestyle='none', marker='none'))
labels.insert(1,'')

plt.legend(lines,labels,numpoints=1, loc=4,ncol=1)

plt.show()

An other option is to create two legends as here and then displace them using bbox_to_anchor keyword here

(lines, labels) = plt.gca().get_legend_handles_labels()
leg1 = plt.legend(lines[:1], labels[:1], bbox_to_anchor=(0,0,0.8,1), loc=1)
leg2 = plt.legend(lines[1:], labels[1:], bbox_to_anchor=(0,0,1,1), loc=1)
gca().add_artist(leg1)

doing it I get without the need of add any on other object.