Pyqtgraph is a powerful library for creating interactive 2D and 3D visualizations in Python. In this tutorial, we will learn how to plot data curves in Pyqtgraph and create stunning data visualizations in PyQt.
Step 1: Install Pyqtgraph
Before we start plotting data curves in Pyqtgraph, make sure you have Pyqtgraph installed. You can install Pyqtgraph using the following command:
pip install pyqtgraphStep 2: Import the necessary modules
In order to plot data curves in Pyqtgraph, you need to import the necessary modules. Here is an example of how to import Pyqtgraph and PyQt modules:
import pyqtgraph as pg
from PyQt5.QtWidgets import QApplicationStep 3: Create a simple PyQt application
Next, we need to create a simple PyQt application to display the data curves. Here is an example of how to create a PyQt application:
app = QApplication([])Step 4: Create a Pyqtgraph plot widget
Now, we need to create a Pyqtgraph plot widget where we will plot our data curves. Here is an example of how to create a simple plot widget:
plot_widget = pg.PlotWidget()
plot_widget.show()Step 5: Plot data curves on the plot widget
Now that we have created a plot widget, we can start plotting data curves on it. Here is an example of how to plot a simple data curve:
data = [1, 2, 3, 4, 5]
plot_widget.plot(data)This will plot a simple line plot using the data provided in the list.
Step 6: Customize the plot
You can further customize the plot by changing the line color, line width, line style, etc. Here is an example of how to customize the plot:
plot_widget.plot(data, pen=(255, 0, 0), width=2, style=pg.QtCore.Qt.DashLine)This will plot the data curve with a red color, a line width of 2, and a dashed line style.
Step 7: Add labels and legends to the plot
You can also add labels and legends to the plot to make it more informative. Here is an example of how to add labels and legends to the plot:
plot_widget.setLabel('left', 'Y-axis')
plot_widget.setLabel('bottom', 'X-axis')
plot_widget.addLegend()This will add labels to the X and Y axes and a legend to the plot.
Step 8: Add multiple data curves to the plot
You can add multiple data curves to the plot by plotting them one after the other. Here is an example of how to add multiple data curves to the plot:
data1 = [1, 2, 3, 4, 5]
data2 = [5, 4, 3, 2, 1]
plot_widget.plot(data1, pen=(255, 0, 0), width=2, style=pg.QtCore.Qt.DashLine, name='Data1')
plot_widget.plot(data2, pen=(0, 255, 0), width=2, style=pg.QtCore.Qt.SolidLine, name='Data2')This will plot two data curves with different colors, line styles, and legends on the plot widget.
Step 9: Run the PyQt application
Finally, you need to run the PyQt application to display the plot widget with the data curves. Here is an example of how to run the PyQt application:
app.exec_()This will start the PyQt application and display the plot widget with the data curves.
That’s it! You have successfully plotted data curves in Pyqtgraph and created stunning data visualizations in PyQt. Feel free to explore more features of Pyqtgraph and create more complex data visualizations.
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Kindly show how to ADD a secondary Y Axis in PyQt5 and pyqtgraph
Any suggestions how to plot live, real-time data using de-queue/pipes? I have a process that receives data from the serial port that I want to send to pyqtgraph for fast plotting!
For example, the github Haschtl/RealTimeOpenControl :
from collections import deque
from PyQt5 import QtWidgets, QtCore, QtGui
import stack
import pyqtgraph as pg
import random
class ExampleApp(QtWidgets.QMainWindow, stack.Ui_MainWindow):
def __init__(self):
super().__init__()
self.setupUi(self)
self.graphicsView.getAxis('left').setLabel('Data Value', color='#0000ff')
self.graphicsView.getAxis('bottom').setLabel('time', 's')
self.graphicsView.showGrid(x=True, y=True)
self.graphicsView.setYRange(0,10)
self.graphicsView.addLine(y=5,pen=pg.mkPen('y'))
self.graphicsView.addLine(y=7,pen=pg.mkPen('r'))
self.curve = self.graphicsView.plot()
self.L = deque([0], maxlen=10)
self.t = deque([0], maxlen=10)
self.timer = QtCore.QTimer(self)
self.timer.timeout.connect(self.updateplot)
self.timer.start(500)
self.timer = QtCore.QTimer()
self.timer.setInterval(50)
self.timer.timeout.connect(self.update_plot_data)
self.timer.start()
def update_plot_data(self):
self.x = self.x[1:] # Remove the first y element.
self.x.append(self.x[-1] + 1) # Add a new value 1 higher than the last.
self.y = self.y[1:] # Remove the first
self.y.append( randint(0,100)) # Add a new random value.
self.data_line.setData(self.x, self.y) # Update the data.
def updateplot(self):
val = round(random.uniform(0,10), 2)
self.L.append(val)
self.t.append(self.t[-1]+1)
self.curve.setData(self.t, self.L)
######################
######################
######################
######################
from PyQt5 import QtWidgets, QtCore
from pyqtgraph import PlotWidget, plot
import pyqtgraph as pg
import sys # We need sys so that we can pass argv to QApplication
import os
from random import randint
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, *args, **kwargs):
super(MainWindow, self).__init__(*args, **kwargs)
self.graphWidget = pg.PlotWidget()
self.setCentralWidget(self.graphWidget)
self.x = list(range(100)) # 100 time points
self.y = [randint(0,100) for _ in range(100)] # 100 data points
self.graphWidget.setBackground('w')
pen = pg.mkPen(color=(255, 0, 0))
self.data_line = self.graphWidget.plot(self.x, self.y, pen=pen)
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
######################
######################
######################
######################
## –– coding: utf-8 ––
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from pyqtgraph import PlotWidget
import pyqtgraph
import numpy as np
import serial
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.plot_data = {
'ax':np.full(100, 0),
'ay':np.full(100, 0),
'az':np.full(100, 0),
'gx':np.full(100, 0),
'gy':np.full(100, 0),
'gz':np.full(100, 0),
'mx':np.full(100, 0),
'my':np.full(100, 0),
'mz':np.full(100, 0),
't' :np.arange(100)
}
self.plot_data_color = {
'ax':'#FF0000',
'ay':'#00FF00',
'az':'#0000FF',
'gx':'#DDDD00',
'gy':'#00DDDD',
'gz':'#DD00DD',
'mx':'#808020',
'my':'#208080',
'mz':'#802080'
}
self.resize(600, 600)
self.setStyleSheet("QMainWindow {background: 'white';}")
self.serial = serial.Serial('COM3', 115200, timeout=None)
# leyout
self.centralwidget = QtWidgets.QWidget(self)
self.setCentralWidget(self.centralwidget)
self.verticalLayout = QtWidgets.QVBoxLayout(self.centralwidget)
# pot widget
self.plotwidget = { axis:PlotWidget(self) for axis in ['a','g','m'] }
titles = { 'a':'Acceleration','g':'Gyro','m':'Geomagnetism' }
for key in self.plotwidget:
self.plotwidget[key].setBackground("#FFFFFFFF")
plotitem = self.plotwidget[key].plotItem
plotitem.setLabels(bottom='time', left=titles[key])
plotitem.getAxis('bottom').setPen( pyqtgraph.mkPen(color='#000000') )
plotitem.getAxis('left').setPen( pyqtgraph.mkPen(color='#000000') )
# leyout
self.verticalLayout.addWidget(self.plotwidget['a'])
self.verticalLayout.addWidget(self.plotwidget['g'])
self.verticalLayout.addWidget(self.plotwidget['m'])
# timer
self.timer = QtCore.QTimer()
self.timer.timeout.connect(self.update_data)
self.timer.start(50)
def update_data(self):
# stop timer
self.timer.stop()
# clear
self.plotwidget['a'].clear()
self.plotwidget['g'].clear()
self.plotwidget['m'].clear()
# get serial
try:
line = self.serial.readline().decode()
data = { data.split(':')[0]:data.split(':')[1] for data in line.split(',') }
# increase time
self.plot_data['t'] = np.append( self.plot_data['t'][1:], self.plot_data['t'][-1]+1 )
# add data
for key in self.plot_data:
if key == 't':
continue
self.plot_data[key] = np.append( self.plot_data[key][1:], float(data[key]) )
# set data
self.plotwidget[key[0]].addItem(
pyqtgraph.PlotDataItem(
x=self.plot_data['t'], y=self.plot_data[key],
pen=pyqtgraph.mkPen(color=self.plot_data_color[key], width=3), antialias=True
)
)
except:
pass
# start timer
self.timer.start(50)
def main():
app = QtWidgets.QApplication(sys.argv)
mainwindow = MainWindow(None)
mainwindow.show()
app.exec()
if _name_ == '__main__':
main()
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