In this article we will see how we can create line graph in the PyQtGraph module. PyQtGraph is a graphics and user interface library for Python that provides functionality commonly required in designing and science applications. Its primary goals are to provide fast, interactive graphics for displaying data (plots, video, etc.) and second is to provide tools to aid in rapid application development (for example, property trees such as used in Qt Designer).
A line chart or line plot or line graph or curve chart is a type of chart which displays information as a series of data points called ‘markers’ connected by straight line segments. It is a basic type of chart common in many fields. Line graph is created with the help of plot class in PyQtGraph.
In order to plot the bar graph in PyQtGraph we have to do the following
1. Importing the PyQtgraph module
2. Creating a plot window
3. Create or get the plotting data i.e horizontal and two vertical data for two lines
4. Set range to the plot window
5. Plot the line on the plot window and specifying properties of the line
Below is the implementation
Python3
# importing pyqtgraph as pgimport pyqtgraph as pg# importing QtCore and QtGui from the pyqtgraph modulefrom pyqtgraph.Qt import QtCore, QtGui# importing numpy as npimport numpy as np# define the datatitle = "Lazyroar PyQtGraph"# y values to plot by line 1y = [2, 8, 6, 8, 6, 11, 14, 13, 18, 19]# y values to plot by line 2y2 = [3, 1, 5, 8, 9, 11, 16, 17, 14, 16]x = range(0, 10)# create plot window objectplt = pg.plot()# showing x and y gridsplt.showGrid(x = True, y = True)# adding legendplt.addLegend()# set properties of the label for y axisplt.setLabel('left', 'Vertical Values', units ='y')# set properties of the label for x axisplt.setLabel('bottom', 'Horizontal Values', units ='s')# setting horizontal rangeplt.setXRange(0, 10)# setting vertical rangeplt.setYRange(0, 20)# setting window title to the plot windowplt.setWindowTitle(title)# plotting line in green color# with dot symbol as x, not a mandatory fieldline1 = plt.plot(x, y, pen ='g', symbol ='x', symbolPen ='g', symbolBrush = 0.2, name ='green')# plotting line2 with blue color# with dot symbol as o line2 = plt.plot(x, y2, pen ='b', symbol ='o', symbolPen ='b', symbolBrush = 0.2, name ='blue')# main methodif __name__ == '__main__': # importing system import sys # Start Qt event loop unless running in interactive mode or using if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'): QtGui.QApplication.instance().exec_() |
Output :
