14. tk Radiobutton

See: https://docs.python.org/3/library/tkinter.html#tkinter.Radiobutton
See: https://www.geeksforgeeks.org/radiobutton-in-tkinter-python/

14.1. Usage

The tkinter.Radiobutton widget provides a radio button that allows the user to select one option from a group of choices.
To create a Radio button widget the general syntax is
(assuming import via "import tkinter as tk"):
radiobutton_widget = tk.Radiobutton(parent, option=value)
parent is the window or frame object.
Options can be passed as parameters separated by commas.
Each radio button should have a unique value.
When the button is selected, this value is stored in the shared variable.

14.2. Using radio buttons

../_images/radio_buttons1.png
This code creates one group of radio buttons in a frame and a second group in root window below the frame.
Each radio button in a group has its own value.
All radio buttons in the group share the same variable.
Selecting a radio button stores its value in the shared variable.
To group radio buttons together, set the variable option to the same StringVar (or IntVar) for each radio button. e.g. variable=option_grp1_var.
A StringVar is commonly used when the radio button values are strings.
An IntVar is commonly used when the values are integers.
All radio buttons in the group must share the same control variable so only one option can be selected at a time.
To preselect the first radio button in the group use: option_grp1_var.set("Option 1").
Set the indicatoron option to 0, to display the widget as a regular push button instead of a circular radio button.
Set the indicatoron option to 1, to make the radio buttons look like radio buttons.
A for loop is used to create each group of radio buttons since they have the same formatting options apart from the text and value options which are taken care of by the loop variable, option.
import tkinter as tk
from tkinter import font


# Create the main window
root = tk.Tk()
root.title("Option Buttons")

# Create a frame with a background color
frame = tk.Frame(root, bg="light blue")
frame.pack(anchor="nw", padx=10, pady=10)

# Define a font style
font_style = ("Lucida Grande", 18)

# Create a StringVar to hold the selected option
option_grp1_var = tk.StringVar(value="Option 1")  # Set a default value for the variable

# Define the options
options_grp1 = ["Option 1", "Option 2", "Option 3"]

# Create and pack the radio buttons
for option in options_grp1:
    button = tk.Radiobutton(frame, text=option, value=option, variable=option_grp1_var,
                            bg="white", fg="black", font=font_style,
                            indicatoron=1, padx=10, pady=5)
    button.pack(anchor="nw", side="left", padx=5, pady=5)

# Run the main event loop
root.mainloop()

Tasks

  1. Modify the code to display four radio buttons vertically, one beneath the other.

Modify the code to display four radio buttons vertically, one beneath the other.

import tkinter as tk
from tkinter import font

# Create the main window
root = tk.Tk()
root.title("Radio Buttons Question")
root.geometry("300x300")

# Create a frame with a background color
frame = tk.Frame(root, bg="light blue")
frame.pack(anchor="nw", padx=10, pady=10)

# Define a font style
font_style = ("Lucida Grande", 18)

# Create a StringVar to hold the selected option
option_var = tk.StringVar(value="Option 1")  # set a default value

# Define the options
options = ["Option 1", "Option 2", "Option 3", "Option 4"]

# Create and pack the radio buttons
for option in options:
    button = tk.Radiobutton(frame, text=option, value=option, variable=option_var,
                            bg="white", fg="black", font=font_style,
                            indicatoron=1, padx=10, pady=5)
    button.pack(anchor="nw", side="top", padx=5, pady=5)

# Run the main event loop
root.mainloop()

14.3. Methods

radiobutton_widget.select()
Selects the radiobutton.
Sets the associated control variable to this radiobutton's value.
radiobutton_widget.deselect()
Deselects the radiobutton.
Sets the associated control variable to an empty value.
This is mainly useful when no radiobutton in the group should be selected.
radiobutton_widget.flash()
Briefly flashes the radiobutton several times.
Useful for drawing the user's attention to the widget.
radiobutton_widget.invoke()
Simulates the user selecting the radiobutton.
Sets the associated control variable to the radiobutton's value and calls the function specified by the command option, if one exists.
Returns the value returned by the callback function.
radiobutton_widget.config(option=value)
Changes one or more widget options after creation.

14.4. Control variable methods

variable.get()
Returns the currently selected value.
variable.set(value)
Selects the radiobutton whose value matches value.
If no radiobutton has a matching value, none of the radiobuttons are selected.

14.5. Parameter syntax

radiobutton_widget = tk.Radiobutton(parent, option=value)
parent is the window or frame object.
Options can be passed as parameters separated by commas.

Parameters:

activebackground
Syntax: radiobutton_widget = tk.Radiobutton(parent, activebackground="color")
Description: Sets the background color of the radiobutton when it is active.
Default: SystemButtonFace
Example: radiobutton_widget = tk.Radiobutton(root, activebackground="lightblue")
activeforeground
Syntax: radiobutton_widget = tk.Radiobutton(parent, activeforeground="color")
Description: Sets the foreground color of the radiobutton when it is active.
Default: SystemWindowText
Example: radiobutton_widget = tk.Radiobutton(root, activeforeground="blue")
anchor
Syntax: radiobutton_widget = tk.Radiobutton(parent, anchor="position")
Description: Sets the anchor position for the text and indicator.
Default: center
Example: radiobutton_widget = tk.Radiobutton(root, anchor="w")
background
Syntax: radiobutton_widget = tk.Radiobutton(parent, background="color")
Description: Sets the background color of the radiobutton.
Default: SystemButtonFace
Example: radiobutton_widget = tk.Radiobutton(root, background="lightyellow")
bd
Syntax: radiobutton_widget = tk.Radiobutton(parent, bd=border_width)
Description: Sets the border width of the radiobutton.
Default: 2
Example: radiobutton_widget = tk.Radiobutton(root, bd=5)
bg
Syntax: radiobutton_widget = tk.Radiobutton(parent, bg="color")
Description: Sets the background color of the radiobutton.
Default: SystemButtonFace
Example: radiobutton_widget = tk.Radiobutton(root, bg="lightyellow")
bitmap
Syntax: radiobutton_widget = tk.Radiobutton(parent, bitmap="bitmap_name")
Description: Sets a bitmap image to be displayed on the radiobutton.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, bitmap="error")
borderwidth
Syntax: radiobutton_widget = tk.Radiobutton(parent, borderwidth=width)
Description: Sets the width of the border around the radiobutton.
Default: 2
Example: radiobutton_widget = tk.Radiobutton(root, borderwidth=3)
command
Syntax: radiobutton_widget = tk.Radiobutton(parent, command=function)
Description: Specifies a function to be called when the radiobutton is selected. Do not include parentheses after the function name.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, command=my_function)
compound
Syntax: radiobutton_widget = tk.Radiobutton(parent, compound="position")
Description: Specifies how to display the image and text (if both are set).
Default: none
Example: radiobutton_widget = tk.Radiobutton(root, compound="left")
cursor
Syntax: radiobutton_widget = tk.Radiobutton(parent, cursor="cursor_type")
Description: Sets the mouse cursor when hovering over the radiobutton.
Default: arrow
Example: radiobutton_widget = tk.Radiobutton(root, cursor="hand2")
disabledforeground
Syntax: radiobutton_widget = tk.Radiobutton(parent, disabledforeground="color")
Description: Sets the foreground color when the radiobutton is disabled.
Default: SystemDisabledText
Example: radiobutton_widget = tk.Radiobutton(root, disabledforeground="gray")
fg
Syntax: radiobutton_widget = tk.Radiobutton(parent, fg="color")
Description: Sets the foreground color of the radiobutton (text color).
Default: SystemWindowText
Example: radiobutton_widget = tk.Radiobutton(root, fg="black")
font
Syntax: radiobutton_widget = tk.Radiobutton(parent, font=("font_name", size, "style"))
Description: Specifies the font type, size, and style for the text of the radiobutton.
Default: TkDefaultFont
Example: radiobutton_widget = tk.Radiobutton(root, font=("Arial", 12, "bold"))
foreground
Syntax: radiobutton_widget = tk.Radiobutton(parent, foreground="color")
Description: Sets the foreground color of the radiobutton (text color).
Default: SystemWindowText
Example: radiobutton_widget = tk.Radiobutton(root, foreground="black")
height
Syntax: radiobutton_widget = tk.Radiobutton(parent, height=value)
Description: Sets the height of the radiobutton.
Default: 0 (automatically determined)
Example: radiobutton_widget = tk.Radiobutton(root, height=2)
highlightbackground
Syntax: radiobutton_widget = tk.Radiobutton(parent, highlightbackground="color")
Description: Sets the background color of the radiobutton when it does not have focus.
Default: SystemButtonFace
Example: radiobutton_widget = tk.Radiobutton(root, highlightbackground="gray")
highlightcolor
Syntax: radiobutton_widget = tk.Radiobutton(parent, highlightcolor="color")
Description: Sets the color of the highlight when the radiobutton has focus.
Default: SystemWindowFrame
Example: radiobutton_widget = tk.Radiobutton(root, highlightcolor="blue")
highlightthickness
Syntax: radiobutton_widget = tk.Radiobutton(parent, highlightthickness=thickness)
Description: Sets the thickness of the highlight border.
Default: 1
Example: radiobutton_widget = tk.Radiobutton(root, highlightthickness=2)
image
Syntax: radiobutton_widget = tk.Radiobutton(parent, image="image_name")
Description: Sets an image to be displayed on the radiobutton.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, image=my_image)
indicatoron
Syntax: radiobutton_widget = tk.Radiobutton(parent, indicatoron=1)
Description: Determines whether the circular radio button indicator is shown. Set to 0 to display the widget as a push button.
Default: 1
Example: radiobutton_widget = tk.Radiobutton(root, indicatoron=0)
justify
Syntax: radiobutton_widget = tk.Radiobutton(parent, justify="position")
Description: Sets the justification of the text (left, center, right).
Default: center
Example: radiobutton_widget = tk.Radiobutton(root, justify="right")
offrelief
Syntax: radiobutton_widget = tk.Radiobutton(parent, offrelief="style")
Description: Sets the relief style for the indicator when off.
Default: raised
Example: radiobutton_widget = tk.Radiobutton(root, offrelief="flat")
overrelief
Syntax: radiobutton_widget = tk.Radiobutton(parent, overrelief="style")
Description: Sets the relief style for the indicator when hovered over.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, overrelief="sunken")
padx
Syntax: radiobutton_widget = tk.Radiobutton(parent, padx=padding_value)
Description: Sets the horizontal padding within the radiobutton.
Default: 1
Example: radiobutton_widget = tk.Radiobutton(root, padx=10)
pady
Syntax: radiobutton_widget = tk.Radiobutton(parent, pady=padding_value)
Description: Sets the vertical padding within the radiobutton.
Default: 1
Example: radiobutton_widget = tk.Radiobutton(root, pady=10)
relief
Syntax: radiobutton_widget = tk.Radiobutton(parent, relief="style")
Description: Sets the border style of the radiobutton. Options include flat, raised, sunken, groove, ridge.
Default: flat
Example: radiobutton_widget = tk.Radiobutton(root, relief="raised")
selectcolor
Syntax: radiobutton_widget = tk.Radiobutton(parent, selectcolor="color")
Description: Sets the color of the indicator when the radiobutton is selected.
Default: SystemWindow
Example: radiobutton_widget = tk.Radiobutton(root, selectcolor="lightgreen")
selectimage
Syntax: radiobutton_widget = tk.Radiobutton(parent, selectimage="image_name")
Description: Sets an image to be displayed when the radiobutton is selected.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, selectimage=my_selected_image)
state
Syntax: radiobutton_widget = tk.Radiobutton(parent, state="state_type")
Description: Sets the state of the radiobutton. Options include normal, disabled, or active.
Default: normal
Example: radiobutton_widget = tk.Radiobutton(root, state="disabled")
takefocus
Syntax: radiobutton_widget = tk.Radiobutton(parent, takefocus=1)
Description: Allows the radiobutton to take focus on click.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, takefocus=1)
text
Syntax: radiobutton_widget = tk.Radiobutton(parent, text="label")
Description: Sets the text label for the radiobutton.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, text="Option 1")
textvariable
Syntax: radiobutton_widget = tk.Radiobutton(parent, textvariable=variable)
Description: Associates a variable with the text of the radiobutton.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, textvariable=my_text_var)
tristateimage
Syntax: radiobutton_widget = tk.Radiobutton(parent, tristateimage="image_name")
Description: Sets an image to be displayed for a tristate radiobutton.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, tristateimage=my_tristate_image)
tristatevalue
Syntax: radiobutton_widget = tk.Radiobutton(parent, tristatevalue=value)
Description: Sets the value for the tristate option of the radiobutton.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, tristatevalue=2)
underline
Syntax: radiobutton_widget = tk.Radiobutton(parent, underline=index)
Description: Specifies the index of the character to underline in the text.
Default: -1 (no underline)
Example: radiobutton_widget = tk.Radiobutton(root, underline=0)
value
Syntax: radiobutton_widget = tk.Radiobutton(parent, value=radio_value)
Description: Specifies the value assigned to the shared control variable when this radio button is selected.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, value=1)
variable
Syntax: radiobutton_widget = tk.Radiobutton(parent, variable=control_variable)
Description: Specifies the shared control variable (such as StringVar or IntVar) used to determine which radio button in the group is selected.
Default: None
Example: radiobutton_widget = tk.Radiobutton(root, variable=my_var)
width
Syntax: radiobutton_widget = tk.Radiobutton(parent, width=width_value)
Description: Sets the width of the radiobutton.
Default: 0 (automatically determined)
Example: radiobutton_widget = tk.Radiobutton(root, width=30)
wraplength
Syntax: radiobutton_widget = tk.Radiobutton(parent, wraplength=pixel_value)
Description: Sets the maximum line length for text in pixels.
Default: 0 (no wrapping)
Example: radiobutton_widget = tk.Radiobutton(root, wraplength=100)

14.6. Default options

Code to display the default value for each Radiobutton option is shown below.
import tkinter as tk

root = tk.Tk()

widget = tk.Radiobutton(root)
widget_options = widget.keys()

for option in widget_options:
    print(f"{option}: {widget.cget(option)}")  # cget retrieves the current value of the option