In this article we will see how we can create a graph item in PyQTGraph. 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 Graph is a non-linear data structure consisting of nodes and edges. The nodes are sometimes also referred to as vertices and the edges are lines or arcs that connect any two nodes in the graph. Graph consists of a finite set of vertices(or nodes) and set of Edges which connect a pair of nodes.
We can create a graphic layout widget with the help of command given below
# creating graphics layout widget win = pg.GraphicsLayoutWidget()
In order to plot the video we have to do the following
- Import the pyqtgraph, pyqt5 and numpy module.
- Create a main window class.
- Create a graphic layout widget and add image view box to it.
- Create a graph item and add it to the view box.
- Set the positions of nodes and edges i.e connections and set symbols to them.
- Create a grid layout and add the graphic layout window to it with other widgets and set the grid widget as central widget of main window.
Below is the implementation.
Python3
# importing Qt widgetsfrom PyQt5.QtWidgets import *# importing systemimport sys# importing numpy as npimport numpy as np# importing pyqtgraph as pgimport pyqtgraph as pgfrom PyQt5.QtGui import *from PyQt5.QtCore import *import pyqtgraph.ptime as ptime# Image View classclass ImageView(pg.ImageView): # constructor which inherit original # ImageView def __init__(self, *args, **kwargs): pg.ImageView.__init__(self, *args, **kwargs)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("GeeksforLazyroar Graph Item") # setting minimum width label.setMinimumWidth(130) # making label do word wrap label.setWordWrap(True) # setting configuration options pg.setConfigOptions(antialias=True) # creating graphics layout widget win = pg.GraphicsLayoutWidget() # adding view box to the graphic layout widget view = win.addViewBox() # lock the aspect ratio view.setAspectLocked() # creating a graph item graph_item = pg.GraphItem() # adding graph item to the view box view.addItem(graph_item) # Define positions of nodes pos = np.array([ [0, 0], [10, 0], [0, 10], [10, 10], [5, 5], [15, 5] ]) # Define the set of connections in the graph adj = np.array([ [0, 1], [1, 3], [3, 2], [2, 0], [1, 5], [3, 5], ]) # Define the symbol to use for each node (this is optional) symbols = ['o', 'x', 'o', 'o', 't', '+'] # Define the line style for each connection (this is optional) lines = np.array([ (255, 0, 0, 255, 1), (255, 0, 255, 255, 2), (255, 0, 255, 255, 3), (255, 255, 0, 255, 2), (255, 0, 0, 255, 1), (255, 255, 255, 255, 4), ], dtype=[('red', np.ubyte), ('green', np.ubyte), ('blue', np.ubyte), ('alpha', np.ubyte), ('width', float)]) # Update the graph graph_item.setData(pos=pos, adj=adj, pen=lines, size=1, symbol=symbols, pxMode=False) # 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(win, 0, 1, 3, 1) # setting this widget as central widget of the main window self.setCentralWidget(widget)# create pyqt5 appApp = QApplication(sys.argv)# create the instance of our Windowwindow = Window()# start the appsys.exit(App.exec()) |
Output :
