In this video lesson we show how Live Data can be plotted using a PyQt window. Our eventual goal is to bring in live data from the Raspberry Pi Pico W using UDP over WiFi, but to learn the concepts today, we will be generating a live sin wave to show how the plotting works. Here is the code we developed in this lesson:
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import sys import numpy as np import pyqtgraph as pg from PyQt5.QtWidgets import * from PyQt5.QtCore import * numPoints = 200 xStart = 0 xStop = 4*np.pi frequency = 1 Inc = (2*np.pi/numPoints) count=0 incR=1 incG=2 x=np.linspace(xStart,xStop,numPoints) ySin=np.sin(frequency*x) ySin2 = np.sin(frequency*x + 2*np.pi/3) ySin3 = np.sin(frequency*x + 4*np.pi/3) def updatePlot(): global numPoint,xStart,xStop,Inc,frequency,count xStart=xStart + Inc xStop=xStop + Inc x =np.linspace(xStart, xStop , numPoints) ySin=np.sin(frequency*x+count*incR/100*frequency) ySin2 = np.sin(frequency*x + 2*np.pi/3+count*incG/100*frequency) ySin3 = np.sin(frequency*x + 4*np.pi/3) plotSin.setData(x, ySin) plotSin2.setData(x, ySin2) plotSin3.setData(x, ySin3) count=count+1 def updateFrequency(value): global frequency, sliderLabel frequency = value/10 sliderLabel.setText("Frequency: "+str(frequency)+" Hz") app=QApplication(sys.argv) window = QWidget() window.setWindowTitle("The Magic of Sin Waves") window.setGeometry(100,100,800,600) layout = QVBoxLayout(window) sliderLabel=QLabel("Frequency: 1 Hz") sliderLabel.setStyleSheet("font-size: 40px;") layout.addWidget(sliderLabel) slider = QSlider(Qt.Horizontal) slider.setMinimum(1) slider.setMaximum(40) slider.setValue(10) slider.valueChanged.connect(updateFrequency) layout.addWidget(slider) graphWidget =pg.PlotWidget() layout.addWidget(graphWidget) plotSin=graphWidget.plot(x,ySin,pen=pg.mkPen('r',width=4)) plotSin2=graphWidget.plot(x,ySin2,pen=pg.mkPen('g',width=4)) plotSin3=graphWidget.plot(x,ySin3,pen=pg.mkPen('b',width=4)) graphWidget.setYRange(-1.25,1.25) timer = QTimer() timer.timeout.connect(updatePlot) timer.start(100) window.setLayout(layout) window.show() sys.exit(app.exec_()) |