PyQtGraph - Adding Spots in Scatter Plot Graph

Last Updated : 19 Nov, 2021

In this article, we will see how we can add spots to a scatter plot 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.). A scatter plot (aka scatter chart, scatter graph) uses dots to represent values for two different numeric variables. It is a type of plot or mathematical diagram using Cartesian coordinates to display values for typically two variables for a set of data. The position of each dot on the horizontal and vertical axis indicates values for an individual data point. Adding spots doesn't reset the data, it appends the spots in data.

We can create a plot window and create a scatter plot graph on it with the help of commands given below.

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

# creating a scatter plot graph of size = 10
scatter = pg.ScatterPlotItem(size=10)

In order to do this we use addPoints method with the scatter plot graph object
Syntax : scatter.addPoints(x_data, y_data)
Argument : It takes two lists as argument
Return : It returns None

Below is the implementation.

Python3

# importing Qt widgets
from PyQt5.QtWidgets import *

# importing system
import sys

# importing numpy as np
import numpy as np

# importing pyqtgraph as pg
import pyqtgraph as pg
from PyQt5.QtGui import *
from PyQt5.QtCore import *


class Window(QMainWindow):

    def __init__(self):
        super().__init__()

        # setting title
        self.setWindowTitle("PyQtGraph")

        # setting geometry
        self.setGeometry(100, 100, 600, 500)

        # icon
        icon = QIcon("skin.png")

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

        # calling method
        self.UiComponents()

        # showing all the widgets
        self.show()

    # method for components
    def UiComponents(self):

        # creating a widget object
        widget = QWidget()

        # creating a label
        label = QLabel("Geeksforgeeks Scatter Plot")

        # making label do word wrap
        label.setWordWrap(True)

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

        # number of points
        n = 300

        # creating a scatter plot item
        # of size = 10
        # using brush to enlarge the of green color
        scatter = pg.ScatterPlotItem(
            size=10, brush=pg.mkBrush(30, 255, 35, 255))

        # data for x-axis
        x_data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

        # data for y-axis
        y_data = [5, 4, 6, 4, 3, 5, 6, 6, 7, 8]

        # adding spots to the scatter plot
        scatter.addPoints(x_data, y_data)

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

        # Creating a grid layout
        layout = QGridLayout()

        # minimum width value of the label
        label.setMinimumWidth(130)

        # setting this layout to the widget
        widget.setLayout(layout)

        # adding label in the layout
        layout.addWidget(label, 1, 0)

        # plot window goes on right side, spanning 3 rows
        layout.addWidget(plot, 0, 1, 3, 1)

        # setting this widget as central widget 
        # of the main window
        self.setCentralWidget(widget)


# create pyqt5 app
App = QApplication(sys.argv)

# create the instance of our Window
window = Window()

# start the app
sys.exit(App.exec())