Displaying Pi decimal number based off counter

Question

Currently a beginner in python.

I'm trying to create a simple tkinter application based on pi (3.14) Every time they press "Next Digit" it increases the counter +1 and displays the next decimal number.

# Import the Tkinter functions
from tkinter import *


#####backend function
global counter
counter = 0
pi = '159265358979323846'


def pi_decimal():
    while counter > 0
         pass
def Decimals():
    global counter
    counter +=1
    display_decimal['text'] = counter


# Create a window
application_window = Tk()

# Give the window a title
application_window.title('PI')

# create a button for application window
my_button = Button(application_window,
                   text = 'Next Digit', command = Decimals)

#create a row that shows the number
number_pi = Label(application_window, text = pi)
display_decimal = Label(application_window, text = counter)

#put button into the window
display_decimal.pack()
number_pi.pack()
my_button.pack()

I'm trying to figure out how to go through the list of decimals of upto 18 adding onto 3.14, for instance. counter 0 = 3.14, counter 1 = 3.141, counter 2 = 3.1415 etc. Any kind of help is appreciated :)

Answer 1

You could do something like this:

Your app was mostly missing a call to mainloop.

# Import the Tkinter functions
import tkinter as tk


def decimals():
    global counter
    counter += 1
    try:
        text = pi[counter]
    except IndexError:
        counter = 0
        text = ''
    display_decimal['text'] = f"PI decimal value: {text}"
    display_decimal_ndx['text'] = f"PI decimal index: {counter}" 


if __name__ == '__main__':

    # backend function
    counter = 0
    pi = '159265358979323846'

    # Create a window
    application_window = tk.Tk()

    # Give the window a title
    application_window.title('PI')

    # create a button for application window
    my_button = tk.Button(application_window,
                          text='Next Digit', command=decimals)

    # create a row that shows the number
    number_pi = tk.Label(application_window, text = pi)
    display_decimal = tk.Label(application_window, text='')
    display_decimal_ndx = tk.Label(application_window, text=counter)

    # put button into the window
    display_decimal.pack()
    display_decimal_ndx.pack()
    number_pi.pack()
    my_button.pack()

    application_window.mainloop()

Note:

You may want to consider using import tkinter as tk instead of cluttering the global namespace.
A try/except block in the function decimals() avoids pesky index errors when the enumeration is done.
A label shows which decimal is shown, and another shows its value.
The enumeration resets to the first decimal once it is done.

Edit:

You could do something like this in order to add a display of number Pi that updates the number of decimals displayed as we press the button:

import tkinter as tk


def decimals():
    global counter
    counter += 1
    try:
        text = pi[counter]
    except IndexError:
        counter = 4
        text = ''
    display_decimal['text'] = f"PI decimal value: {text}"
    display_decimal_ndx['text'] = f"PI decimal index: {counter}"
    number_pi['text'] = pi[:counter+1]


if __name__ == '__main__':

    # backend function
    counter = 4
    pi = '3.14159265358979323846'

    # Create a window
    application_window = tk.Tk()

    # Give the window a title
    application_window.title('PI')

    # create a button for application window
    my_button = tk.Button(application_window,
                          text='Next Digit', command=decimals)

    # create a row that shows the number
    number_pi = tk.Label(application_window, text = pi[:counter+1])
    display_decimal = tk.Label(application_window, text='')
    display_decimal_ndx = tk.Label(application_window, text=counter)

    # put button into the window
    display_decimal.pack()
    display_decimal_ndx.pack()
    number_pi.pack()
    my_button.pack()

    application_window.mainloop()