#! /usr/bin/env python3

from tkinter import *
import os

Computers = [
    'RaspberryPi3',
    'PiUbuntu',
    'Thylacoleo']

def sel():
    cmd = "open afp://" + Computers[var.get()] + ".local"
    os.system( cmd )

root = Tk()      # create tkinter object
root.title("Connect to Computer")   # give the window a title...
root.minsize(250, 100)
var = IntVar()
button=0

for cc in Computers:
    R1 = Radiobutton(root, text=cc, variable=var, value=button, command=sel)
    R1.pack( anchor = W )
    button += 1

root.mainloop()

Computers = {
    'RaspberryPi3': 'Pi3',
    'PiUbuntu': 'PiUbuntu',
    'Ubuntu-T': 'Thylaco'
    }

def sel():
    print("selection", tvar)
    selection = "You selected the option " + tvar

root = Tk()      # create tkinter object
root.title("Connect to Computer")   # give the window a title...
root.minsize(250, 100)
# var = IntVar()
# tvar = StringVar()
tvar = str()
button=0

for cc in list(Computers.keys()):
#     R1 = Radiobutton(root, text=cc, variable=var, value=button, command=sel)
    R1 = Radiobutton(root, text=cc, variable=tvar, value=cc, command=sel)
#   R1 = Radiobutton(root, text=cc, textvariable=tvar, command=sel)
    R1.pack( anchor = W )

root.mainloop()