如何在tkinter嵌入式matplotlib图形中使​​用按钮在两个图形之间交替？

Question

我希望能够在嵌入式tkinter matplotlib图形中使​​用按钮来从一个图形切换到另一个图形。我编写的代码不会用第二张图替换第一张图，而只是将第二张图添加到第一张图的下面。我如何才能按下按钮以将第二张图替换为第一张图，而不仅仅是在第二张图的下方添加第二张图？这是我的代码：

import matplotlib
matplotlib.use("TkAgg")
import matplotlib.pyplot as plt
import numpy as np
from tkinter import *
from matplotlib.backends.backend_tkagg import (
    FigureCanvasTkAgg, NavigationToolbar2Tk)
# Implement the default Matplotlib key bindings.
from matplotlib.backend_bases import key_press_handler



def graph_one():
    t = np.arange(0.0, 2.0, 0.01)
    s = 1 + np.sin(2 * np.pi * t)

    fig, ax = plt.subplots()
    ax.plot(t, s)

    ax.set(xlabel='time (s)', ylabel='voltage (mV)',
           title='Graph One')

    #plt.show()
    return fig


def graph_two():
    t = np.arange(0.0, 2.0, 0.01)
    s = 1 + np.cos(2 * np.pi * t)

    fig, ax = plt.subplots()
    ax.plot(t, s)

    ax.set(xlabel='time (s)', ylabel='voltage (mV)',
           title='Graph Two')

    #plt.show()
    return fig

class matplotlibSwitchGraphs:
    def __init__(self, master):
        self.master = master
        self.frame = Frame(self.master)
        self.embed_graph_one()
        self.frame.pack(expand=YES, fill=BOTH)

    def embed_graph_one(self):

        fig = graph_one()

        canvas = FigureCanvasTkAgg(fig, self.master)  
        canvas.draw()
        canvas.get_tk_widget().pack(side=TOP, fill=BOTH, expand=1)

        canvas.mpl_connect("key_press_event", self.on_key_press)

        toolbar = NavigationToolbar2Tk(canvas, self.master)
        toolbar.update()
        canvas.get_tk_widget().pack(side=TOP, fill=BOTH, expand=1)


        self.button = Button(self.master, text="Quit", 
command=self._quit)
        self.button.pack(side=BOTTOM)
        self.button_vol = Button(self.master, text="Switch Graphs", 
command=self.switch_graphs)
        self.button_vol.pack(side=BOTTOM)

    def embed_graph_two(self):

        fig = graph_two()

        canvas = FigureCanvasTkAgg(fig, self.master)  
        canvas.draw()
        canvas.get_tk_widget().pack(side=TOP, fill=BOTH, expand=1)

        canvas.mpl_connect("key_press_event", self.on_key_press)

        toolbar = NavigationToolbar2Tk(canvas, self.master)
        toolbar.update()
        canvas.get_tk_widget().pack(side=TOP, fill=BOTH, expand=1)


        self.button = Button(self.master, text="Quit", 
command=self._quit)
        self.button.pack(side=BOTTOM)
        self.button_switch = Button(self.master, text="Switch Graphs", 
command=self.switch_graphs)
        self.button_switch.pack(side=BOTTOM)


    def on_key_press(event):
        print("you pressed {}".format(event.key))
        key_press_handler(event, canvas, toolbar)

    def _quit(self):
        self.master.quit()  # stops mainloop


    def switch_graphs(self):
        self.embed_graph_two()

def main():
    root = Tk()
    matplotlibSwitchGraphs(root)
    root.mainloop()



if __name__ == '__main__':
    main()

任何帮助将不胜感激。