PyQtGraph – Getting Data of Bar Graph

In this article we will see how we can get data of the bar 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 bar chart or bar graph is a chart or graph that presents categorical data with rectangular bars with heights or lengths proportional to the values that they represent. The bars can be plotted vertically or horizontally. A vertical bar chart is sometimes called a column chart. Bar graph uses two data from two list i.e for x-axis and for the height of the bars.

We can create a plot window and bar graph with the help of commands given below

# creating a pyqtgraph plot window
window = pg.plot()

# creating a bar graph of green color
bargraph = pg.BarGraphItem(x=x, height=y1, width=0.6, brush='g')

In order to do this we use getData method with the bar graph object

Syntax : bargraph.getData()

Argument : It takes no argument

Return : It returns tuple

Below is the implementation

# importing QtGui to use QIcon
from PyQt5.QtGui import * from PyQt5.QtCore import Qt

# importing pyqtgraph as pg
import pyqtgraph as pg

# importing QtCore and QtGui from the pyqtgraph module
from pyqtgraph.Qt import QtCore, QtGui

# importing numpy as np
import numpy as np

import time

# creating a pyqtgraph plot window
window = pg.plot()

# icon for plot window
icon = QIcon("logo.png")

# setting icon to the plot window
window.setWindowIcon(icon)

# setting window geometry
# left = 100, top = 100
# width = 600, height = 500
window.setGeometry(100, 100, 600, 500)

# title for the plot window
title = "GeeksforGeeks PyQtGraph"

# setting window title to plot window
window.setWindowTitle(title)

# create list for y-axis
y1 = [5, 5, 7, 10, 3, 8, 9, 1, 6, 2]

# create horizontal list i.e x-axis
x = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# create pyqt5graph bar graph item
# with width = 0.6
# with bar colors = green
bargraph = pg.BarGraphItem(x = x, height = y1, width = 0.6, brush ='g')

# add item to plot window
# adding bargraph item to the window
window.addItem(bargraph)


# getting data of the bar graph
value = bargraph.getData()

# printing the value
print("Data  : " + str(value))


# main method
if __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 :

Data  : ([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [5, 5, 7, 10, 3, 8, 9, 1, 6, 2])