Python Tkinter Radio Button

What is a Python Tkinter Radio Button?

A radio button is a Python Tkinter GUI widget that allows the user to choose only one of a predefined set of mutually exclusive options. This is in contrast to the Check Button which allows you to pick more than one.

Syntax

Rbttn = Radiobutton(master, option..........)

Below is a compilation of all the main options available for Radio Buttons.

Creating a Tkinter Radio Button

Here we’ll discuss how to create a standard Tkinter Radio Button. If you’ve done Check-buttons, the syntax is almost identical. The only difference is in their control variables.

You can create a control variable by using the IntVar() function. You can also use StringVar() if you wish to return a string value.

It’s important for Radio Buttons to share the same control variable. This is because only one radio button should be selected at a time (Because the control variable can only hold one value at a time). If each radio button had a unique control variable, it would be no different from a Check Button. However, to differentiate between them, they must have different values.

from tkinter import *

root = Tk()
root.geometry("200x150")
frame = Frame(root)
frame.pack()

Var1 = StringVar()

RBttn = Radiobutton(frame, text = "Option1", variable = Var1,
                    value = 1)
RBttn.pack(padx = 5, pady = 5)

RBttn2 = Radiobutton(frame, text = "Option2", variable = Var1,
                     value = 2)
RBttn2.pack(padx = 5, pady = 5)


root.mainloop()

While they have the same control variable, make sure they have different values. You’ll realize this once you reach the next section.

Retrieving Radio Button Values

A Radio Button returns the value assigned to it while creating it.

There are two ways to retrieve Radio Button values. The first is User-triggered. Meaning, unless the user triggers the appropriate command the values will not be returned. In this case, the User has to press the Submit button for the values to be returned.

Pressing the submit button will call a function that uses the get() method on the control variable that the Radio Buttons share. The get method returns the value that we assigned to the option value when creating the Radio Button.

from tkinter import *

def retrieve():
    print(Var1.get())

root = Tk()
root.geometry("200x150")
frame = Frame(root)
frame.pack()

Var1 = IntVar()

RBttn = Radiobutton(frame, text = "Burger", variable = Var1,
                    value = 1)
RBttn.pack(padx = 5, pady = 5)

RBttn2 = Radiobutton(frame, text = "Pizza", variable = Var1,
                     value = 2)
RBttn2.pack(padx = 5, pady = 5)

Button = Button(frame, text = "Submit", command = retrieve)
Button.pack()

root.mainloop()

The second method involves the use of the inbuilt option within the Radio Button called command. It functions very similar to the example above. In this case, no button is required. Every time the user changes the state of the Radio button, this command will call the appropriate Function.

from tkinter import *

def retrieve():
    print(Var1.get())

root = Tk()
root.geometry("200x150")
frame = Frame(root)
frame.pack()

Var1 = IntVar()

RBttn = Radiobutton(frame, text = "Burger", variable = Var1,
                    value = 1, command = retrieve)
RBttn.pack(padx = 5, pady = 5)

RBttn2 = Radiobutton(frame, text = "Pizza", variable = Var1,
                     value = 2, command = retrieve)
RBttn2.pack(padx = 5, pady = 5)

root.mainloop()

Video Code

The Code from our Video on Tkinter RadioButtons on our YouTube Channel for CodersLegacy.

import tkinter as tk

class Window:
    def __init__(self, master):
        self.master = master

        # Frame
        self.frame = tk.Frame(self.master, width = 200, height = 200)
        self.frame.pack()

        # Radiobutton
        self.var1 = tk.IntVar()

        self.radio = tk.Radiobutton(self.frame, variable = self.var1, value = 1, text = "Option 1", command = self.submit)
        self.radio.place(x = 30, y = 30)

        self.radio2 = tk.Radiobutton(self.frame, variable = self.var1, value = 2, text = "Option 2", command = self.submit)
        self.radio2.place(x = 30, y = 60)


    def submit(self):
        if self.var1.get() == 1:
            print("Option 1 was selected")
        elif self.var1.get() == 2:
            print("Option 2 was selected")


root = tk.Tk()
root.title("Tkinter")

window = Window(root)
root.mainloop()

You can head back to the main Tkinter article using this link. Any questions about the tutorial content can be asked in the comments section below.