PyQt5 hello world example, Python GUI

Make a graphical interface with PyQt?

Graphical interfaces made with PyQt run on: Microsoft Windows, Apple Mac OS X and Linux. We will create a Hello World app with PyQt.

PyQt installation

PyQt is available for both Python 2 (2.7.9 tested) and Python 3.

To install write:

pip3 install pyqt5

With apt-get you can use: python3-pyqt5

PyQt hello world

The app we write will show the message “Hello World” in a graphical window. Import the PyQt5 module.

# https://pythonprogramminglanguage.com/pyqt5-hello-world/
import sys
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QMainWindow, QLabel, QGridLayout, QWidget
from PyQt5.QtCore import QSize    

class HelloWindow(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)

        self.setMinimumSize(QSize(640, 480))    
        self.setWindowTitle("Hello world - pythonprogramminglanguage.com") 

        centralWidget = QWidget(self)          
        self.setCentralWidget(centralWidget)   

        gridLayout = QGridLayout(self)     
        centralWidget.setLayout(gridLayout)  

        title = QLabel("Hello World from PyQt", self) 
        title.setAlignment(QtCore.Qt.AlignCenter) 
        gridLayout.addWidget(title, 0, 0)

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    mainWin = HelloWindow()
    mainWin.show()
    sys.exit( app.exec_() )

The program starts in the main part.

We initialize Qt and create an object of the type HelloWindow.

We call the show() method to display the window.

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    mainWin = HelloWindow()
    mainWin.show()
    sys.exit( app.exec_() )

The HelloWindow class inherits from the class QMainWindow.

We call its super method to initialize the window.

Several class variables are set: size and window title.

We add widgets to the window, including a label widget (QLabel) which displays the message “Hello World”.

If you are new to Python PyQt, then I highly recommend this book.

Download PyQt Examples