PyQtGraph – Scatter Plot Graph

In this article we will see how we can create a scatter plot graph using PyQtGraph module.  PyQtGraph is a graphics and user interface Python library for functionalities commonly required in designing and science applications. Its provides fast, interactive graphics for displaying data (plots, video, etc.). A scatter plot uses dots to represent values for two different numeric variables. It is a type of plot that uses 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. Scatter plots are used to observe relationships between variables.

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

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

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

In order to create a scatter plot graph in pyqtgraph, following steps needs to be followed:

1. Import the pyqtgraph module
2. import other modules as well like numpy and pyqt5
3. Create a main window class
4. Create scatter plot item
5. Create random spots at random position using numpy
6. Add those spots to the scatter plot data
7. Create a grid layout
8. Add scatter plot and additional label to the layout
9. Set layout widget as the central widget
   

Example:

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 *


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 white color with transparency is 50%
        scatter = pg.ScatterPlotItem(
            size=10, brush=pg.mkBrush(255, 255, 255, 120))

        # getting random position
        pos = np.random.normal(size=(2, n), scale=1e-5)

        # creating spots using the random position
        spots = [{'pos': pos[:, i], 'data': 1}
                 for i in range(n)] + [{'pos': [0, 0], 'data': 1}]

        # adding points to the scatter plot
        scatter.addPoints(spots)

        # 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())

Output :