在Tkinter上有没有办法，当我在画布上绘制一个新的图形时，前一个图形会被破坏，而不是堆叠在右边？

Question

当我在画布上绘制一个新图形时，上一个图形是否会被销毁，而不是堆叠在右侧？我尝试了一些东西，比如使用.destroy()，但似乎没有任何效果。。。每次我点击绘图按钮时，它都会将新图形放到右侧。我不知道如何解决它，所以任何帮助都是非常受欢迎的

下面是我按下按钮时发生的情况的图片：另一个图形添加到右侧。我只想要一个（当我按下按钮时得到的最后一个）

这是我的密码：

class StartPage(tk.Frame):
    
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        button2 = ttk.Button(self, text="draw",command=lambda:  func1())
        button2.pack()
        entry1 = Entry(self,width = 20)
        entry1.pack()
        entry2 = Entry(self,width = 20)
        entry2.pack()
        entry3 = Entry(self,width = 20)
        entry3.pack()

        def func1():
            rho = float(entry1.get())
            sigma = float(entry2.get())
            beta = float(entry3.get())
            def f(state, t):
                x, y, z = state  
                return sigma * y, z-sigma, rho*x * y - beta * z  

            state0 = [4.0, 3.0, 2.0]
            t = np.arange(0.0, 40.0, 0.01)

            states = odeint(f, state0, t)

            fig = plt.figure()
            canvas = FigureCanvasTkAgg(fig, self)
            canvas.draw() 
            ax = fig.gca(projection='3d')
            ax.plot(states[:, 0], states[:, 1], states[:, 2])
            canvas.get_tk_widget().pack(side=tk.LEFT,fill=tk.BOTH, expand=True)

Answer 1

您可以创建fig和canvas外部func1()并更新其中的图形：

class StartPage(tk.Frame):
    
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        button2 = ttk.Button(self, text="draw",command=lambda: func1())
        button2.pack()
        entry1 = tk.Entry(self, width=20)
        entry1.pack()
        entry2 = tk.Entry(self, width=20)
        entry2.pack()
        entry3 = tk.Entry(self, width=20)
        entry3.pack()

        fig = plt.figure()
        canvas = FigureCanvasTkAgg(fig, self)

        def func1():
            rho = float(entry1.get())
            sigma = float(entry2.get())
            beta = float(entry3.get())
            def f(state, t):
                x, y, z = state  
                return sigma * y, z-sigma, rho*x * y - beta * z  

            state0 = [4.0, 3.0, 2.0]
            t = np.arange(0.0, 40.0, 0.01)

            states = odeint(f, state0, t)

            plt.clf()  # clear current figure
            ax = fig.gca(projection='3d')
            ax.plot(states[:, 0], states[:, 1], states[:, 2])
            canvas.draw() # update the figure
            canvas.get_tk_widget().pack(fill=tk.BOTH, expand=True)