在一行中锚定相同 plot 的两个图例

Question

I have a plot with two legends that are not of the same height. I would like to place them such that their titles start at the same place on the y-axis. I know I could go and manually change bbox_to_anchor=(-0.1, -0.3) but I would have to redo it each time there are minor changes. Is there no way to set this automatically?

fig = plt.figure(1)
ax = fig.add_subplot(1, 1, 1)
xticks = mtick.FormatStrFormatter(fmt)
yticks = mtick.FormatStrFormatter(fmt)
x1 = plt.scatter([1,2],[2,3], color='b')
x2 = plt.scatter([2,3],[4,3], color='r')
x3 = plt.scatter([1,3],[4,5], color='k')
x4 = plt.scatter(0, 0, color='white')
marker1 = 'marker 1'
marker2 = 'marker 2'
marker3 = 'marker 3'
plt.xlabel("x axis")
plt.ylabel("y axis")
marker4 = ('some text that needs to go here too'+'\n'+'and is very important and just way too long so that it wont ever look good')
legend_two = plt.legend([x1, x4],[marker1, marker4],fontsize=8,
                           title='some other title', title_fontsize=10,
                           bbox_to_anchor=(0.5, -0.3), ncol=1, loc="center left", borderaxespad=0)
plt.legend([x1,x2,x3], [marker1,marker2,marker3], fontsize=8,
           title='some title', title_fontsize=10,
           bbox_to_anchor=(-0.1, -0.3), ncol=3, loc="center left", borderaxespad=0)
plt.gca().add_artist(legend_two)
plt.tight_layout()
plt.show()

Answer 1

In this case, if the coordinate axis of the bounding box is used as the FIGURE reference, it will be displayed at a fixed position without being affected by others. See here for more information on coordinate axes. For other examples of responses, please refer to this .

import matplotlib.pyplot as plt
from matplotlib import ticker

fmt = '$%g$'
fig = plt.figure(1)
ax = fig.add_subplot(1, 1, 1)
xticks = ticker.FormatStrFormatter(fmt)
yticks = ticker.FormatStrFormatter(fmt)
x1 = plt.scatter([1,2],[2,3], color='b')
x2 = plt.scatter([2,3],[4,3], color='r')
x3 = plt.scatter([1,3],[4,5], color='k')
x4 = plt.scatter(0, 0, color='white')
marker1 = 'marker 1'
marker2 = 'marker 2'
marker3 = 'marker 3'
plt.xlabel("x axis")
plt.ylabel("y axis")
marker4 = ('some text that needs to go here too'+'\n'+'and is very important and just way too long so that it wont ever look good')
legend_two = plt.legend([x1, x4],[marker1, marker4],
                        fontsize=8,
                        title='some other title',
                        title_fontsize=10,
                        bbox_to_anchor=(0.5, 0.0), #update
                        bbox_transform=fig.transFigure, # update
                        ncol=1,
                        loc="upper left",
                        borderaxespad=0)
plt.legend([x1,x2,x3], [marker1,marker2,marker3],
           fontsize=8,
           title='some title',
           title_fontsize=10,
           bbox_to_anchor=(0.0, 0.0), # update
           bbox_transform=fig.transFigure, # update
           ncol=3,
           loc="upper left",
           borderaxespad=0)
plt.gca().add_artist(legend_two)
plt.tight_layout()
plt.show()