Python 3 Radio button controlling label text - python-3.x

Question

I am in the process of learning Python3 and more of a necessity, the TkInter GUI side. I was working my way through a book by James Kelly, when I encountered this problem. All his examples made a new window with just label/canvas/check box etc which seemed to work OK.
But as I wanted to experiment in a more real world scenario I put most things on one window. This where I encountered my problem. I can not get the radio button in the frame to alter the wording of a label in the parent window.
Complete code is:-
#! /usr/bin/python3
from tkinter import *
def win_pos(WL,WH,xo=0,yo=0) :
# Screen size & position procedure
# Screen size
SW = home.winfo_screenwidth()
SH = home.winfo_screenheight()
# 1/2 screen size
sw=SW/2
sh=SH/2
# 1/2 window size
wl=WL/2
wh=WH/2
# Window position
WPx=sw-wl+xo
WPy=sh-wh+yo
# Resulting string
screen_geometry=str(WL) + "x" + str(WH) + "+" + str(int(WPx)) + "+" \ + str(int(WPy))
return screen_geometry
# Create a window
home=Tk()
home.title("Radio buttons test")
# Set the main window
home.geometry(win_pos(600,150))
lab1=Label(home)
lab1.grid(row=1,column=1)
fraym1=LabelFrame(home, bd=5, bg="red",relief=SUNKEN, text="Label frame text")
fraym1.grid(row=2,column=2)
laybl1=Label(fraym1, text="This is laybl1")
laybl1.grid(row=0, column=3)
var1=IntVar()
R1=Radiobutton(fraym1, text="Apple", variable=var1, value=1)
R1.grid(row=1, column=1)
R2=Radiobutton(fraym1, text="Asus", variable=var1, value=2)
R2.grid(row=1, column=2)
R3=Radiobutton(fraym1, text="HP", variable=var1, value=3)
R3.grid(row=1, column=3)
R4=Radiobutton(fraym1, text="Lenovo", variable=var1, value=4)
R4.grid(row=1, column=4)
R5=Radiobutton(fraym1, text="Toshiba", variable=var1, value=5)
R5.grid(row=1, column=5)
# Create function used later
def sel(var) :
selection="Manufacturer: "
if var.get() > 0 :
selection=selection + str(var.get())
lab1.config(text=selection)
R1.config(command=sel(var1))
R2.config(command=sel(var1))
R3.config(command=sel(var1))
R4.config(command=sel(var1))
R5.config(command=sel(var1))
R1.select()
mainloop()
I realise that there is room for improvement using classes/functions but I need to get this resolved in my head before I move on. As it can be hopefully seen, I'm not a complete novice to programming, but this is doing my head in.
Can a solution, and reasoning behind the solution, be given?

Answer 1

You can modify your label's text by assigning the same variable class object, var1 as its textvariable option as well but since lab1's text is slightly different, try removing:
R1.config(command=sel(var1))
R2.config(command=sel(var1))
R3.config(command=sel(var1))
R4.config(command=sel(var1))
R5.config(command=sel(var1))
R1.select()
and modify sel to:
def sel(*args) :
selection="Manufacturer: "
selection=selection + str(var1.get())
lab1.config(text=selection)
and then call var1.trace("w", sel) somewhere before mainloop as in:
...
var1.trace("w", sel)
mainloop()
Also for a simple example:
import tkinter as tk
root = tk.Tk()
manufacturers = ["man1", "man2", "man3", "man4", "man5"]
lbl = tk.Label(root, text="Please select a manufacturer.")
lbl.pack()
# create an empty dictionary to fill with Radiobutton widgets
man_select = dict()
# create a variable class to be manipulated by radiobuttons
man_var = tk.StringVar(value="type_default_value_here_if_wanted")
# fill radiobutton dictionary with keys from manufacturers list with Radiobutton
# values assigned to corresponding manufacturer name
for man in manufacturers:
man_select[man] = tk.Radiobutton(root, text=man, variable=man_var, value=man)
#display
man_select[man].pack()
def lbl_update(*args):
selection="Manufacturer: "
selection=selection + man_var.get()
lbl['text'] = selection
#run lbl_update function every time man_var's value changes
man_var.trace('w', lbl_update)
root.mainloop()
Example with label's identical to that of radiobutton's value:
import tkinter as tk
root = tk.Tk()
# radiobutton group will the button selected with the value=1
num = tk.IntVar(value=1)
lbl = tk.Label(root, textvariable=num)
zero = tk.Radiobutton(root, text="Zero", variable=num, value=0)
one = tk.Radiobutton(root, text="One", variable=num, value=1)
#display
lbl.pack()
zero.pack()
one.pack()
root.mainloop()