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:
- Import the pyqtgraph module
- import other modules as well like numpy and pyqt5
- Create a main window class
- Create scatter plot item
- Create random spots at random position using numpy
- Add those spots to the scatter plot data
- Create a grid layout
- Add scatter plot and additional label to the layout
- 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( "w3wiki 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 :
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