Updating PyQt5 GUI with Live Data

Question

I created a PyQt5 GUI using QtDesigner and converted it to Python. I was planning to update and display the value from the sensor reading from the Raspberry Pi. Since the GUI is in a loop, there is no way I can update data from outside that loop. Currently I used the code below where I use the QTimer widget that executes the function every given interval. Is this solution appropriate or not? What other methods are available to accomplish this task?

from PyQt5 import QtCore, QtGui, QtWidgets
from uimainwindow import Ui_MainWindow

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):

    numTest=0;

    def __init__(self):
        QtWidgets.QMainWindow.__init__(self)
        self.setupUi(self)
        QtCore.QTimer.singleShot(1000, self.getSensorValue)

    def getSensorValue(self):
        print(self.numTest)
        self.numTest=self.numTest+1
        QtCore.QTimer.singleShot(1000, self.getSensorValue)

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

Answer 1

To use a QTimer which calls a member function periodically:

1. Make a member variable of QTimer.

2. Set interval of QTimer to the intended delay.

3. Connect getSensorValue() as signal handler to QTimer.timeout().

4. Start QTimer member.

Demo test-QTimer.py:

#!/usr/bin/python3

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QLabel
from PyQt5.QtCore import QTimer

class MainWindow(QMainWindow):
  # constructor
  def __init__(self):
    QMainWindow.__init__(self)
    # counter
    self.i = 0
    # add QLabel
    self.qLbl = QLabel('Not yet initialized')
    self.setCentralWidget(self.qLbl)
    # make QTimer
    self.qTimer = QTimer()
    # set interval to 1 s
    self.qTimer.setInterval(1000) # 1000 ms = 1 s
    # connect timeout signal to signal handler
    self.qTimer.timeout.connect(self.getSensorValue)
    # start timer
    self.qTimer.start()

  def getSensorValue(self):
    self.i += 1
    # print('%d. call of getSensorValue()' % self.i)
    self.qLbl.setText('%d. call of getSensorValue()' % self.i)

qApp = QApplication(sys.argv)
# setup GUI
qWin = MainWindow()
qWin.show()
# run application
sys.exit(qApp.exec_())

Tested in cygwin on Windows 10: