Tkinter Radiobutton - On Change of Selection

Tkinter Radiobutton - On change of selection

You can set a callback function to execute whenever there is a change in the selection in the Radiobutton group.

To set a callback function to execute whenever there is a change in the selection in the Radiobutton group in Tkinter, set the command parameter of the Radiobutton widgets with the callback function.

radio_button1 = tk.Radiobutton(window, text="Option 1", variable=radio_var, value="Option 1", command=on_radio_change)

In the above code, the Radiobutton is set with a callback function of on_radio_change that executes whenever this Radiobutton is selected. So, if you give the same callback function for all the Radiobutton widgets in a group, we can track the "on selection change" event of the Radiobutton group.

In this tutorial, you will learn how to set a callback function for the event of selection change in Radiobutton group in Tkinter, with an example program.

Example

In this example, we shall create a group of three Radiobutton widgets with values: Option 1, Option 2, and Option 3. These three Radiobutton widgets are set with on_radio_change function for the command parameter. Whenever there is a change in the selection, this function is called. And in this callback function, we print the newly selected value.

Program

import tkinter as tk

# Create the main window
window = tk.Tk()
window.geometry("300x200")
window.title("PythonExamples.org")

def on_radio_change():
    selected_option = radio_var.get()
    print(f"Selected option : {selected_option}")

# Create a variable to hold the selected option
radio_var = tk.StringVar()

# Create Radiobuttons
radio_button1 = tk.Radiobutton(window, text="Option 1", variable=radio_var, value="Option 1", command=on_radio_change)
radio_button2 = tk.Radiobutton(window, text="Option 2", variable=radio_var, value="Option 2", command=on_radio_change)
radio_button3 = tk.Radiobutton(window, text="Option 3", variable=radio_var, value="Option 3", command=on_radio_change)

# Pack the Radiobuttons
radio_button1.pack()
radio_button2.pack()
radio_button3.pack()

# Start the Tkinter event loop
window.mainloop()

Output in Windows

Output on MacOS

Tkinter Radiobutton - On Change of Selection - GUI Example

Select Option 2.

Tkinter Radiobutton - On Change of Selection - User selects "Option 2" — Tkinter Radiobutton - User selects "Option 2"

The callback function is called and the selected option is printed to the standard output.

Now, select an other option, say Option 3.

Tkinter Radiobutton - On Change of Selection - User selects "Option 3" — Tkinter Radiobutton - User selects "Option 3"

Summary

In this Python Tkinter tutorial, we have seen how to set a callback function to execute whenever there is a change in the selection in Radiobutton group, with examples.