sliderdemo.py

import tkinter as tk
from tkinter import ttk


# root window
root = tk.Tk()
root.geometry('300x200')
root.resizable(False, False)
root.title('Slider Demo')


root.columnconfigure(0, weight=1)
root.columnconfigure(1, weight=3)


# slider current value
current_value = tk.DoubleVar()


def get_current_value():
    return '{: .2f}'.format(current_value.get())


def slider_changed(event):
    value_label.configure(text=get_current_value())


# label for the slider
slider_label = ttk.Label( root, text='Slider:')
slider_label.grid(column=0, row=0, sticky='w')

#  slider
slider = ttk.Scale(root, from_=0, to=100, orient='horizontal',
                   command=slider_changed, variable=current_value)

slider.grid(column=1, row=0, sticky='we')

# current value label
current_value_label = ttk.Label(root, text='Current Value:')
current_value_label.grid(row=1, columnspan=2, sticky='n', ipadx=10, ipady=10)

# value label
# value_label = ttk.Label(root, text=get_current_value())  # text CALLS A FUNCTION!!!
value_label = ttk.Label(root, text=current_value.get())  # text CALLS A FUNCTION!!!
value_label.grid(row=2, columnspan=2, sticky='n')


root.mainloop()