#!/usr/bin/env python3#importmatplotlib.pyplotaspltimportnumpyasnpfrommatplotlib.textimportTextt=np.linspace(0,1)y1=2*np.sin(2*np.pi*t)y2=4*np.sin(2*np.pi*2*t)fig,ax=plt.subplots()title=ax.set_title('Click this title once to control draggable legend')title.set_picker(5)(line1, )=ax.plot(t,y1,lw=2,label='1 Hz')(line2, )=ax.plot(t,y2,lw=2,label='2 Hz')leg=ax.legend(fancybox=True,shadow=True)#leg.set_picker(None)  # no effect on set_draggable artefactlines= [line1,line2]map_legend_to_ax= {}# Will map legend lines to original lines.pickradius=5# Points (Pt). How close the click needs to be to trigger an event.forlegend_line,ax_lineinzip(leg.get_lines(),lines):legend_line.set_picker(pickradius)# Enable picking on the legend line.map_legend_to_ax[legend_line]=ax_linedefon_pick(event):# On the pick event, find the original line corresponding to the legend# proxy line, and toggle its visibility.legend_line=event.artistifisinstance(event.artist,Text):leg.set_picker(0)print(f"Picker set on legend:{leg.get_picker()}\n""Now, only mouse_press on legend makes it move.")# Do nothing if the source of the event is not a legend line.iflegend_linenotinmap_legend_to_ax:returnax_line=map_legend_to_ax[legend_line]visible=notax_line.get_visible()ax_line.set_visible(visible)# Change the alpha on the line in the legend, so we can see what lines# have been toggled.legend_line.set_alpha(1.0ifvisibleelse0.2)fig.canvas.draw()#leg.set_picker(None) # no effect on set_draggable artefactfig.canvas.mpl_connect('pick_event',on_pick)#leg.set_picker(None) # no effect on set_draggable artefact# Works even if the legend is draggable. This is independent from picking legend lines.leg.set_draggable(True)#leg.set_picker(None) # kills set_draggable#leg.set_draggable(True) # cannot restore set_draggable#leg.set_picker(0) # creates expected draggable-legend-behaviourprint (f"Legend picker:{leg.get_picker()};\n""legend can be moved by mouse_drag far away from legend.")plt.show()