PyQt | Technology Tutorials

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:

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_())

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_())

In this Video Lesson we show you how to create a Graphical User Interface to allow you to interact with your python program and hardware projects. The GUI can have buttons, slider bars, radio buttons, drop down menus, and many more widgets. In this lesson we show you how to install the package, and step-by-step instructions on how to use it. For your convenience, here is the code we developed in the lesson.

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtCore import Qt
import time

def greenButtonPressed():
    print("green button clicked")
def yellowButtonPressed():
    print("yellow button clicked")
def redButtonPressed():
    print("red button clicked")
def offButtonPressed():
    print("off button clicked")
def sliderValueChanged(val):
    frequency=val/10
    sliderLabel.setText("Frequency: "+str(frequency)+" Hz")
    print("Frequency: ",frequency)

app = QApplication(sys.argv)
window = QWidget()
window.setWindowTitle("My Grand Widget")
window.setGeometry(100,100,800,600)

widgetBox=QVBoxLayout(window)
buttonBox=QHBoxLayout()

greenButton = QPushButton("Green Button")
greenButton.setStyleSheet("background-color: green; color: white;")
greenButton.clicked.connect(greenButtonPressed)
buttonBox.addWidget(greenButton)

yellowButton = QPushButton("Yellow Button")
yellowButton.setStyleSheet("background-color: yellow; color: black;")
yellowButton.clicked.connect(yellowButtonPressed)
buttonBox.addWidget(yellowButton)

redButton = QPushButton("Red Button")
redButton.setStyleSheet("background-color: red; color: white;")
redButton.clicked.connect(redButtonPressed)
buttonBox.addWidget(redButton)

offButton = QPushButton("Off Button")
offButton.setStyleSheet("background-color: black; color: white;")
offButton.clicked.connect(offButtonPressed)

slider = QSlider(Qt.Horizontal)
slider.setMinimum(1)
slider.setMaximum(40)
slider.setValue(10)
slider.setTickPosition(QSlider.TicksBelow)
slider.setTickInterval(5)
slider.valueChanged.connect(sliderValueChanged)


sliderLabel=QLabel("Frequency: 1.0 HZ")
sliderLabel.setAlignment(Qt.AlignCenter)
sliderLabel.setStyleSheet("font-size: 24px;padding 2px;")

widgetBox.addLayout(buttonBox)
widgetBox.addWidget(sliderLabel)
widgetBox.addWidget(slider)
widgetBox.addStretch()

window.setLayout(widgetBox)
window.show()
sys.exit(app.exec_())

import sys

from PyQt5.QtWidgets import *

from PyQt5.QtCore import Qt

import time

def greenButtonPressed():

print("green button clicked")

def yellowButtonPressed():

print("yellow button clicked")

def redButtonPressed():

print("red button clicked")

def offButtonPressed():

print("off button clicked")

def sliderValueChanged(val):

frequency=val/10

sliderLabel.setText("Frequency: "+str(frequency)+" Hz")

print("Frequency: ",frequency)

app = QApplication(sys.argv)

window = QWidget()

window.setWindowTitle("My Grand Widget")

window.setGeometry(100,100,800,600)

widgetBox=QVBoxLayout(window)

buttonBox=QHBoxLayout()

greenButton = QPushButton("Green Button")

greenButton.setStyleSheet("background-color: green; color: white;")

greenButton.clicked.connect(greenButtonPressed)

buttonBox.addWidget(greenButton)

yellowButton = QPushButton("Yellow Button")

yellowButton.setStyleSheet("background-color: yellow; color: black;")

yellowButton.clicked.connect(yellowButtonPressed)

buttonBox.addWidget(yellowButton)

redButton = QPushButton("Red Button")

redButton.setStyleSheet("background-color: red; color: white;")

redButton.clicked.connect(redButtonPressed)

buttonBox.addWidget(redButton)

offButton = QPushButton("Off Button")

offButton.setStyleSheet("background-color: black; color: white;")

offButton.clicked.connect(offButtonPressed)

slider = QSlider(Qt.Horizontal)

slider.setMinimum(1)

slider.setMaximum(40)

slider.setValue(10)

slider.setTickPosition(QSlider.TicksBelow)

slider.setTickInterval(5)

slider.valueChanged.connect(sliderValueChanged)

sliderLabel=QLabel("Frequency: 1.0 HZ")

sliderLabel.setAlignment(Qt.AlignCenter)

sliderLabel.setStyleSheet("font-size: 24px;padding 2px;")

widgetBox.addLayout(buttonBox)

widgetBox.addWidget(sliderLabel)

widgetBox.addWidget(slider)

widgetBox.addStretch()

window.setLayout(widgetBox)

window.show()

sys.exit(app.exec_())

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Technology Tutorials

Tag Archives: PyQt

Plotting Live Data in Python Using PyQT

PyQt Essentials for Absolute Beginners

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