Python matplotlib tkinter - 按钮不更新图形

Question

我正在编写一个小程序，目的是在整个过程中定期更新 matplotlib 图。为此，我打算使用 clear() 并重新绘制图形。 clear 函数在从创建图形的方法中调用时确实有效，但在从按钮调用时不起作用，即使图形作为参数给出。

下面是最基本形式的可运行代码来说明问题。
在这种情况下，单击“更新”按钮什么也不做。我将如何修复该按钮以清除图形？

import matplotlib.pyplot as plt 
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
import tkinter as tk
import numpy as np

class MainWindow(tk.Frame):
    def __init__(self, master = None):
        tk.Frame.__init__(self, master)
        self.add_graph()

    def add_graph(self):         
        fig_sig = plt.figure(figsize=(4,2))
        graph = fig_sig.add_subplot(111)
        y_values = [0,1,2,3,4,5]   
        x_values = [1,2,3,4,5,6]
        graph.plot(x_values, y_values)
        canvas = FigureCanvasTkAgg(fig_sig, master=root)
        canvas_widget=canvas.get_tk_widget()   
        canvas_widget.grid(row = 1, column = 0, columnspan = 3)
        canvas.draw()
        self.add_widgets(root, graph)
        #graph.clear()  # Calling graph.clear() here does clear the graph

    def add_widgets(self, parent, graph):
        update_btn = tk.Button(parent, text = "Update", command = lambda: self.update_graph(graph))
        update_btn.grid(row = 8, column = 3)

    def update_graph(self, graph):
        graph.clear()   # calling graph.clear() here does nothing

root = tk.Tk()
oberflaeche = MainWindow(master = root)
oberflaeche.mainloop()   

Answer 1

在这种情况下，您需要“更新” Canvas 。

将您的 Canvas 定义为:self.canvas = FigureCanvasTkAgg(fig_sig, master=root)
并“更新”它:

def update_graph(self, graph):
    graph.clear()   # calling graph.clear() here does nothing
    self.canvas.draw()