Python PyQt radio button example

Python PyQt Connecting Signals to Slots: Exercise-10 with Solution

Write a Python program that creates a PyQt application with a radio button group. When you select a radio button it should immediately show you which one you picked.

From doc.qt.io:

QApplication Class: The QApplication class manages the GUI application's control flow and main settings.

QWidget Class: The QWidget class is the base class of all user interface objects.

QRadioButton Class: The QRadioButton widget provides a radio button with a text label.

QVBoxLayout Class: The QVBoxLayout class lines up widgets vertically.

QLabel Class: The QLabel widget provides a text or image display.

Sample Solution:

Python Code:

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QRadioButton, QVBoxLayout, QLabel

class RadioButtonApp(QWidget):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Radio Button Example")
        self.setGeometry(100, 100, 300, 200)  # (x, y, width, height)

        layout = QVBoxLayout()

        # Create radio buttons for options
        self.option1_radio = QRadioButton("Python", self)
        self.option2_radio = QRadioButton("Java", self)
        self.option3_radio = QRadioButton("C++", self)

        layout.addWidget(self.option1_radio)
        layout.addWidget(self.option2_radio)
        layout.addWidget(self.option3_radio)

        # Create a label to display the selected option
        self.selected_option_label = QLabel("Selected Option: None", self)
        layout.addWidget(self.selected_option_label)

        # Connect the radio buttons' toggled signal to a slot that updates the label
        self.option1_radio.toggled.connect(lambda: self.update_selected_option("Python"))
        self.option2_radio.toggled.connect(lambda: self.update_selected_option("Java"))
        self.option3_radio.toggled.connect(lambda: self.update_selected_option("C++"))

        self.setLayout(layout)

    def update_selected_option(self, option):
        if option:
            self.selected_option_label.setText(f"Selected Option: {option}")

def main():
    app = QApplication(sys.argv)
    window = RadioButtonApp()
    window.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

• Import the necessary modules from PyQt5.
• Create a custom "QWidget" class named "RadioButtonApp" that builds a radio button group with options.
• Design a layout with three radio buttons for options ('Python', 'Java', 'C++').
• Create a "QLabel" (self.selected_option_label) to display the selected option.
• Connect the toggle signal of each radio button to a slot (self.update_selected_option) that updates the label with the selected option.
• In the main function, we create the PyQt application, instantiate the "RadioButtonApp" class, and show the main window.

Output:

Flowchart:

Python Code Editor:

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