%matplotlibwidgetimportmatplotlib.pyplotaspltimportnumpyasnpfig,ax=plt.subplots()decay=lambdaC,K,x:C*(1-np.exp(-1*K*x))x=np.linspace(0,10,10)# Create a secondary y axis on the righttwin_ax=ax.twinx()forninrange(5):C=n**2+5K=0.75# Plot the exponential decay on left y axisax.plot(x,decay(C,K,x),marker='o',linestyle='--',label=C)# Plot the limit of decay on right y axistwin_ax.axhline(y=C,color='gray')ax.legend()ax.set_xlabel('X')ax.set_ylabel('Measured values')twin_ax.set_ylabel('Theoritical limit')# Align the both left and right y axistwin_ax.set_ylim(ax.get_ylim())################### Issues or bugs# Need to fix the X limits or else# the graph doens't display properly##################print('xlim before fix: {}'.format(ax.get_xlim()))ax.relim()print('xlim after relim(): {}'.format(ax.get_xlim()))# A hack to fix the issue # https://stackoverflow.com/a/27344398/4988010twin_ax.plot(0,0,visible=False)print('xlim after fixing: {}'.format(ax.get_xlim()))plt.show()