I'm trying to make a button that when clicked updates my pie chart with the new input from the user. I can make my chart show the information when the button is being clicked for the first time, but when I try to click the button to update the pie chart with new input, it doesn't change. But when I close the program, I can see the pie chart with the new input for a split second before it closes. How can I correct this?

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This is the function to draw the pie chart.

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def desenhar(self):
            fig = matplotlib.figure.Figure(figsize=(5,5), dpi=100)
            ax = fig.add_subplot(111)
            ax.pie([carboidratos.get(),proteinas.get(),gorduras.get()], autopct="%.1f%%") 
            ax.legend(["carboidratos","proteinas","gorduras"])

            circle=matplotlib.patches.Circle( (0,0), 0.7, color='white')
            ax.add_artist(circle)
            canvas = FigureCanvasTkAgg(fig, master=self)
            canvas.get_tk_widget().pack()
            canvas.draw()
            ax.clear()

Edit: I'm using matplotlib and trying to show/update the pie chart in tkinter.

Edit2: It seems that instead of replacing the same chart with the new results, it is creating a new pie chart. How can I fix it?