爲什麼Matplotlib重繪變慢，當它被嵌入到PyQt5中？

Question

我正在學習如何在PyQt5中嵌入matplotlibAnimation。當我將a example like this嵌入到下面的窗口小部件中時，圖中的約100個點已被添加到ydata列表中。

# coding=utf-8 

import numpy as np 
import matplotlib 
# Make sure that we are using QT5 
matplotlib.use('Qt5Agg') 
from matplotlib.figure import Figure 
from matplotlib.animation import TimedAnimation, FuncAnimation 
from matplotlib.lines import Line2D 
from PyQt5 import QtGui, QtWidgets, QtCore 
import time 

from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as 
               FigureCanvas 
from matplotlib.backends.backend_qt5agg import NavigationToolbar2QT as 
               NavigationToolbar 

定義CustomFigCanvas以將其放入小部件中。

class CustomFigCanvas(FigureCanvas, FuncAnimation): 

    def __init__(self): 

     # The data 
     self.xdata = [] 
     self.ydata = [] 
     self.end = float() 
     self.start = float() 

     # The window 
     self.fig = Figure() 
     self.ax = self.fig.add_subplot(111) 
     self.line, = self.ax.plot([], [], lw=2) 
     self.ax.grid() 
     # ax1 settings 
     self.ax.set_xlabel('time') 
     self.ax.set_ylabel('raw data') 

     FigureCanvas.__init__(self, self.fig) 
     FuncAnimation.__init__(self, self.fig, self.Update, self.data_gen,           
        blit=False,interval=40,repeat=False,init_func=self.init) 
     FigureCanvas.setSizePolicy(self, QtWidgets.QSizePolicy.Expanding, 
            QtWidgets.QSizePolicy.Expanding) 

    def data_gen(self): 

     self.cnt = 0 
     self.t = 0 
     while self.cnt < 1000: 
      print(self.cnt) 
      self.cnt += 1 
      self.t += 0.1 
      self.y = np.sin(2 * np.pi * self.t) * np.exp(-self.t/10.) 
      yield self.t, self.y 

    def init(self): 
     self.ax.set_ylim(-1.1, 1.1) 
     self.ax.set_xlim(0, 10) 
     del self.xdata[:] 
     del self.ydata[:] 
     self.line.set_data(self.xdata, self.ydata) 
     return self.line, 

    def Update(self, data): 
     # update the data 
     self.end = time.time() 
     print(self.end - self.start) 
     t, y = data 
     self.xdata.append(t) 
     self.ydata.append(y) 
     xmin, xmax = self.ax.get_xlim() 

     if t >= xmax: 
      self.ax.set_xlim(xmin, 2 * xmax) 
      self.ax.figure.canvas.draw() 
      self.line.set_data(self.xdata, self.ydata) 
     self.start = time.time() 
     print('---------') 
     return self.line, 

定義PyQt Widget。

class MplCanvasWrapper(QtWidgets.QDialog): 

    def __init__(self, parent=None): 
     QtWidgets.QDialog.__init__(self, parent) 
     self.canvas = CustomFigCanvas() 
     self.vbl = QtWidgets.QVBoxLayout() 
     self.ntb = NavigationToolbar(self.canvas, parent) 
     self.btnStart = QtWidgets.QPushButton() 
     self.btnStart.setText('start') 
     self.btnPause = QtWidgets.QPushButton() 
     self.btnPause.setText('end') 

     self.vbl.addWidget(self.ntb) 
     self.vbl.addWidget(self.canvas) 
     self.vbl.addWidget(self.btnStart) 
     self.vbl.addWidget(self.btnPause) 

     self.setLayout(self.vbl) 

     self.btnStart.clicked.connect(self.startPlot) 
     self.btnPause.clicked.connect(self.pausePlot) 

     self.dataX = [] 
     self.dataY = [] 

    def startPlot(self): 
     pass 

    def pausePlot(self): 
     pass 


if __name__ == "__main__": 
    import sys 
    app = QtWidgets.QApplication(sys.argv) 
    test_widget = MplCanvasWrapper() 
    test_widget.show() 
    sys.exit(app.exec_()) 

示例平滑地移動。 我怎樣才能改變我的代碼，使移動順利？

Answer 1

把這段代碼放在'if'之外就是問題的解決方案。

self.line.set_data（self.xdata，self.ydata）