from tkinter import *
import csv

def add_number():
    num = num_box.get()
    if num.isdigit():
        num_list.insert('end', num)
        num_box.delete(0, 'end')
        num_box.focus()
    else:
        num_box.delete(0, 'end')
        num_box.focus()

def clear_list():
    num_list.delete(0, 'end')
    num_box.focus()

def save_list():
    with open('/tmp/nums.csv', '+a') as file:
        tmp_list = num_list.get(0, 'end')
        item = 0
        for _ in tmp_list:
            newrecord = tmp_list[item]+'\n'
            file.write(str(newrecord))
            item += 1
        file.close()

window = Tk()
window.title("Lista de Números")
window.geometry("400x200")

label1 = Label(text="Ingresa un nro.")
label1.place(x=20, y=20, width=100, height=25)

num_box = Entry()
num_box.place(x=120, y=20, width=100, height=25)
num_box.focus()

button1 = Button(text="Agregar", command=add_number)
button1.place(x=250, y=20, width=100, height=25)

num_list = Listbox()
num_list.place(x=120, y=50, width=100, height=100)

button2 = Button(text="Limpiar", command=clear_list)
button2.place(x=250, y=50, width=100, height=25)

button3 = Button(text="Guardar", command=save_list)
button3.place(x=250, y=80, width=100, height=25)

window.mainloop()