Radio Buttons won't select jpg - python-2.7

Question

Shortened the code to minimum for the question. I want to toggle between images to apply on the canvas using radiobuttons. The code will only apply the images if I enter the image name, (ex. tkimg2) into the 'stamp' event. The radiobuttons are not selecting the images, nor does the link work if I enter the image name in picture=[]. Do you know why the image name is sufficient in one location and not the other and why the radiobuttons don't work? Thank you for any help
from Tkinter import *
import PIL
from PIL import ImageTk, Image
import random
import os.path
root = Tk()
shapes = []
#load 2 images for stamping
__dir__ = os.path.dirname(os.path.abspath(__file__))
filename = os.path.join(__dir__, 'balloon.jpg')
img = PIL.Image.open(filename)
tkimg=PIL.ImageTk.PhotoImage(img)
filename2 = os.path.join(__dir__, 'bird1.jpg')
img2 = PIL.Image.open(filename2)
tkimg2=PIL.ImageTk.PhotoImage(img2)
picture =[]
image=picture
# A Radiobutton to toggle between images
radio = [0]*2
v = IntVar()
def call():
if int(float(str(v.get())))==1:
picture=tkimg
else:
picture=tkimg2
Label(root, text ="Select an image to place.").grid(row=1, column=0,
columnspan=5, sticky=S)
R1=Radiobutton(root, text="Bird 1", variable=v, value=1, command=call)
R1.grid(row=2, column=0, sticky=N+E)
R1.select()
R2=Radiobutton(root, text="Bird 2", variable=v, value=2, command=call)
R2.grid(row=2, column=1, sticky=N+E)
# A canvas for mouse events and image drawing
canvas = Canvas(root, height=1000, width=1000, bg='#2EEAFF')
canvas.grid(column=5, row=0, rowspan=4, sticky=W)
# Bind a function to the left mouse button down event.
def stamp(event):
canvas.create_image(event.x,event.y,image)
canvas.bind('<ButtonPress-1>', stamp)
# Enter event loop
root.mainloop()

Answer 1

I removed most of the code not relevant to the question and changed the images to ordinary PhotoImages for simplicity. Also I changed the first positioning of the image on the canvas.
If you want to assign a value to a variable inside a function you'll have to make it global or it will not work. The variable will be defined in the local function scope and will be garbage collected when the function ends.
I don't think you can change an image on a canvas by updating the variable you used to create it. That's how a StringVar functions.
As the image is the only widget on the canvas I delete ALL items and then create a new image when I toggle images.
Also: I use Python 3.6 so I spell tkinter without the capital T.
from tkinter import *
root = Tk()
#load 2 images for stamping
tkimg = PhotoImage(file='test.gif') # Test image
tkimg2 = PhotoImage(file='tesu.gif') # Test image
# A Radiobutton to toggle between images
v = IntVar()
def call():
canvas.delete(ALL)
if v.get() == 1:
canvas.create_image((2, 2), image=tkimg, anchor=NW)
else:
canvas.create_image((2, 2), image=tkimg2, anchor=NW)
Label(root, text ="Select an image to place.").grid(row=1, column=0, columnspan=5, sticky=S)
R1=Radiobutton(root, text="Bird 1", variable=v, value=1, command=call)
R1.grid(row=2, column=0, sticky=N+E)
R1.select()
R2=Radiobutton(root, text="Bird 2", variable=v, value=2, command=call)
R2.grid(row=2, column=1, sticky=N+E)
# A canvas for mouse events and image drawing
canvas = Canvas(root, height=200, width=200, bg='#2EEAFF')
canvas.grid(column=5, row=0, rowspan=4, sticky=W)
canvas.create_image((2, 2), image=tkimg, anchor=NW)
# Enter event loop
root.mainloop()