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PyQtGraph – Symbols
  • Last Updated : 01 Nov, 2020

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 line chart is a type of graph which displays information as a series of data points commonly known as markers, connected by straight line segments. A scatter plot uses dots to represent values for two different numeric variables. It is a type of graph, drawn using Cartesian coordinates to display values for typically two variables for a set of data
 

When we create a line graph or scatter plot graph, the points which represent some data needs to be highlighted using certain symbols, by default it is round circle but this can be modified as required. There are a total of 12 symbols which are offered by pyqtgraph which can be used to change symbol as required.
Below are the list of the symbols available in this module:

  • o : Default symbol, round circle symbol 
  • t : Triangle pointing downwards symbol 
  • t1 : Triangle pointing upwards symbol 
  • t2 : Triangle pointing right side symbol 
  • t3 : Triangle pointing left side symbol 
  • s : Square symbol 
  • p : Pentagon symbol 
  • h : Hexagon symbol 
  • star : Star symbol 
  • + : Plus symbol 
  • d : Prism symbol 
  • x : Cross symbol

    This is how they appear on the output screen:

We can create a plot window with the help of commands given below :

plt = pg.plot()

In order to implement the above explained concept, following steps can be followed:
 



  •  Import pyqtgraph, pyqt5 and numpy modules 
  • Create Main window class 
  • Create a plot window object 
  • Add legend to the plot window 
  • Create 12 lines having different points so that they don’t intersect each other and hiving different symbol and colors 
  • Add the plot window and other widget like label to the grid layout
  • Set grid layout widget as the central widget of the main window
     

Example:

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# 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 * from collections import namedtuple
  
  
class Window(QMainWindow):
  
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("PyQtGraph")
  
        # setting geometry
        self.setGeometry(100, 100, 800, 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()
  
        # text
        text = "Geeksforgeeks Different Symbols"
  
        # creating a label
        label = QLabel(text)
  
        # setting minimum width
        label.setMinimumWidth(130)
  
        # making label do word wrap
        label.setWordWrap(True)
  
        # setting pyqtgraph configuration
        pg.setConfigOptions(antialias = True)
  
        # creating a plot window
        plot = pg.plot()
  
        # adding legend to the plot window
        plot.addLegend()
  
        # plot the line1 with symbol o
        # having color blue
        line1 = plot.plot([1, 1, 1, 1, 1], pen =(0, 0, 200), symbolBrush =(0, 0, 200),
                          symbolPen ='w', symbol ='o', symbolSize = 14, name ="symbol ='o'")
  
        # plot the line2 with symbol t
        # having color green
        line2 = plot.plot([2, 2, 2, 2, 2], pen =(0, 128, 0), symbolBrush =(0, 128, 0),
                          symbolPen ='w', symbol ='t', symbolSize = 14, name ="symbol ='t'")
  
        # plot the line3 with symbol t1
        # having color bluegreen
        line3 = plot.plot([3, 3, 3, 3, 3], pen =(19, 234, 201), symbolBrush =(19, 234, 201),
                          symbolPen ='w', symbol ='t1', symbolSize = 14, name ="symbol ='t1'")
  
        # plot the line4 with symbol t2
        # having color purple
        line4 = plot.plot([4, 4, 4, 4, 4], pen =(195, 46, 212), symbolBrush =(195, 46, 212),
                          symbolPen ='w', symbol ='t2', symbolSize = 14, name ="symbol ='t2'")
  
        # plot the line5 with symbol t3
        # having color brownish
        line5 = plot.plot([5, 5, 5, 5, 5], pen =(250, 194, 5), symbolBrush =(250, 194, 5),
                          symbolPen ='w', symbol ='t3', symbolSize = 14, name ="symbol ='t3'")
  
        # plot the line6 with symbol s
        # having color grey
        line6 = plot.plot([6, 6, 6, 6, 6], pen =(54, 55, 55), symbolBrush =(55, 55, 55), symbolPen ='w', symbol ='s', symbolSize = 14,
                  name ="symbol ='s'")
  
        # plot the line7 with symbol p
        # having color sky blue
        line7 = plot.plot([7, 7, 7, 7, 7], pen =(0, 114, 189), symbolBrush =(0, 114, 189),
                         symbolPen ='w', symbol ='p', symbolSize = 14, name ="symbol ='p'")
  
        # plot the line8 with symbol h
        # having color orange
        line8 = plot.plot([8, 8, 8, 8, 8], pen =(217, 83, 25), symbolBrush =(217, 83, 25),
                          symbolPen ='w', symbol ='h', symbolSize = 14, name ="symbol ='h'")
  
        # plot the line9 with symbol star
        # having yellow color
        line9 = plot.plot([9, 9, 9, 9, 9], pen =(237, 177, 32), symbolBrush =(237, 177, 32),
                          symbolPen ='w', symbol ='star', symbolSize = 14, name ="symbol ='star'")
  
        # plot the line10 with symbol +
        # having blueish color
        line10 = plot.plot([10, 10, 10, 10, 10], pen =(126, 47, 142), symbolBrush =(126, 47, 142),
                           symbolPen ='w', symbol ='+', symbolSize = 14, name ="symbol ='+'")
  
        # plot the line11 with symbol d
        # having greensih color
        line11 = plot.plot([11, 11, 11, 11, 11], pen =(119, 172, 48), symbolBrush =(119, 172, 48),
                           symbolPen ='w', symbol ='d', symbolSize = 14, name ="symbol ='d'")
  
        # plot the line12 with symbol x
        # having off white color
        line12 = plot.plot([12, 12, 12, 12, 12], pen =(180, 180, 180), symbolBrush =(180, 180, 180),
                           symbolPen ='w', symbol ='x', symbolSize = 14, name ="symbol ='x'")
  
        # setting x-axis range
        plot.setXRange(-3, 4)
  
        # 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 widow
        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())

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Output : 
 

 

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