为什么我的数据不能用python绘制到qt4的画布上？我已经把货到了

Question

我正在建立一个实时数据采集绘图控制系统。我有一个用pyqt4编写的GUI，有3个控制按钮，一个quit按钮和嵌入的matplotlib图，我应该显示实时数据。数据正在打印到终端屏幕，但从未打印到GUI中。如果我关闭UI，图形将出现，但什么也不显示。plot函数也可以单独工作，只需使用血小板（）图=plt.图（）[定义ax前两者]ax=图add\ U子批次（111）和变化自拔（）至图画布绘制（）

我试过使用pyqt4和pyqt5使用不同的方法。我认为它对展示什么感到困惑。我为GUI设置了主窗口和三个按钮，单独工作，但是如果包含绘图，就不能与它们交互

'''
import sys
from PyQt4 import QtGui, QtCore
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as 
FigureCanvas
import time
import numpy as np
from matplotlib.figure import Figure
import explorerhat
'''
class Window(QtGui.QMainWindow):

    def __init__(self):
        super(Window, self).__init__()
        self.setGeometry(400, 400, 700, 500)
        self.setWindowTitle("PiDAQ")

        ## Define Canvas size and location to be embedded into Main Window
        canvas = Canvas(self, width = 4, height = 4)
        canvas.move(200,20)

        self.show()

 ''' END CLASS'''

class Canvas(FigureCanvas):
    def __init__(self, parent = None, width =5 , height = 5, dpi =100):
        fig = Figure(figsize=(width, height), dpi=dpi)
        self.axes = fig.add_subplot

        FigureCanvas.__init__(self, fig)
        self.setParent(parent)

        self.plot()
'''
     def plot(self):

        t0 = time.time()

        i=0
        print('t0=', t0)
        ax = self.figure.add_subplot(111)

        N=50

        x = np.arange(N)*20/N
        y1 = np.arange(N)*5/N
        y2 = np.arange(N)*5/N

        line1, = self.ax.plot(x, y1, 'b-')
        line2, = self.ax.plot(x, y2, 'r-')

        while True:
            i =+ 1
            V2 = self.explorerhat.analog.one.read()
            V3 = self.explorerhat.analog.two.read()
            V4 = self.explorerhat.analog.three.read()
            V5 = self.explorerhat.analog.four.read()
            if V2 > 2.5:
                output = ' POW!!! '
            else:
                output = ''
            t = time.time()-t0

            if i % N == 0:

                print(i, t, V2, V3, V4, V5, output)
            x[i%N-1] = t

            if i % N == 0:
                y1[-1] = V2
                y2[-1] = V3
                line1.set_xdata(x-x[0])
                line1.set_ydata(y1)
                line2.set_xdata(x-x[0])
                line2.set_ydata(y2)
                self.draw()
            else:
                y1[i%N-1] = V2
                y2[i%N-1] = V3
            time.sleep(0.00001)
 '''

Answer 1

问题是plot函数永远不会返回，因此会阻塞事件循环。你知道吗

Qt的工作原理是让一个无限循环（事件循环）侦听事件，然后将它们分配给偶数个处理程序。事件可以是键盘按下、鼠标单击、重绘请求、TCP通知等。事件处理程序是处理该事件的函数。它们应该很快返回，因为只要它们在运行，Qt就不能处理其他事件（Qt只有一个线程可以处理GUI事件）。不返回的事件处理程序使应用程序“挂起”。有关更详细的解释，请参见this artcicle。你知道吗

由于发生了某些事件（例如，按钮单击事件处理程序发出连接到插槽的单击信号），因此会直接或间接调用所有方法。因此，您编写的所有方法都应该快速返回（例如，一秒钟内返回）。plot函数不返回，因此程序挂起。你知道吗

解决方案是从plot函数中删除while循环，并将内容放在QTimer定期调用的单独方法中。像这样的。你知道吗

import sys
from PyQt4 import QtGui, QtCore
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as 
FigureCanvas
import time
import numpy as np
from matplotlib.figure import Figure
import explorerhat

class Window(QtGui.QMainWindow):

    def __init__(self):
        super(Window, self).__init__()
        self.setGeometry(400, 400, 700, 500)
        self.setWindowTitle("PiDAQ")

        ## Define Canvas size and location to be embedded into Main Window
        canvas = Canvas(self, width = 4, height = 4)
        canvas.move(200,20)

        self.show()
        self.timer = QtCore.QTimer(100) # 100 msec
        selt.timer.timeout.connect(canvas.updatePlot)



class Canvas(FigureCanvas):
    def __init__(self, parent = None, width =5 , height = 5, dpi =100):
        fig = Figure(figsize=(width, height), dpi=dpi)
        self.axes = fig.add_subplot

        FigureCanvas.__init__(self, fig)
        self.setParent(parent)

        self.t0 = time.time()

        self.i=0
        print('t0=', t0)
        ax = self.figure.add_subplot(111)

        N=50

        self.x = np.arange(N)*20/N
        self.self.y1 = np.arange(N)*5/N
        self.y2 = np.arange(N)*5/N

        self.line1, = self.ax.plot(x, y1, 'b-')
        self.line2, = self.ax.plot(x, y2, 'r-')


    def updatePlot(self):
        self.i =+ 1
        V2 = self.explorerhat.analog.one.read()
        V3 = self.explorerhat.analog.two.read()
        V4 = self.explorerhat.analog.three.read()
        V5 = self.explorerhat.analog.four.read()
        if V2 > 2.5:
            output = ' POW!!! '
        else:
            output = ''
        t = time.time()-self.t0

        if self.i % N == 0:
            print(i, t, V2, V3, V4, V5, output)

        x = self.x
        x[i%N-1] = t

        if self.i % N == 0:
            self.y1[-1] = V2
            self.y2[-1] = V3
            self.line1.set_xdata(x-x[0])
            self.line1.set_ydata(y1)
            self.line2.set_xdata(x-x[0])
            self.line2.set_ydata(y2)
            self.draw()
        else:
            self.y1[i%N-1] = V2
            self.y2[i%N-1] = V3

免责声明，我没有运行上面的代码。它可能包含小错误。你知道吗