tkinter GUI (Lights not displaying to my window)

Question

Three lights operate with radio button

Can anyone help me to figure out the cause? The below code gives no error but no output:( On my root other icons appear (which is not included here) but the below portion of code not works?

from tkinter import *


root = Tk()

frame = Frame(root)
frame.pack()

color = StringVar()

 radio_red = Radiobutton(frame, text="Red", bg="red", variable= color, value="R", command= on_RadioChange)
 radio_red.grid(row=10, column=1)

 radio_yellow = Radiobutton(frame, text="Yellow", bg="yellow", variable= color, value="Y", command= on_RadioChange)               
 radio_yellow.grid(row = 10, column = 2)

 radio_green = Radiobutton(frame, text="Green", bg="green", variable= color, value="G", command= on_RadioChange)
 radio_green.grid(row = 10, column = 3)

 canvas = Canvas(root, width=450, height=300, bg="white")
 canvas.pack()

 oval_red = canvas.create_oval(10, 10, 110, 110, fill="white")
 oval_yellow = canvas.create_oval(120, 10, 220, 110, fill="white")
 oval_green = canvas.create_oval(230, 10, 330, 110, fill="white")

  color.set('R')
  canvas.itemconfig(oval_red, fill="red")
        
  root.mainloop()       

def on_RadioChange():
        color = color.get()

        if color == 'R':
            canvas.itemconfig(oval_red, fill="red")
            canvas.itemconfig(oval_yellow, fill="white")
            canvas.itemconfig(oval_green, fill="white")
        elif color == 'Y':
            canvas.itemconfig(oval_red, fill="white")
            canvas.itemconfig(oval_yellow, fill="yellow")
            canvas.itemconfig(oval_green, fill="white")
        elif color == 'G':
            canvas.itemconfig(oval_red, fill="white")
            canvas.itemconfig(oval_yellow, fill="white")
            canvas.itemconfig(oval_green, fill="green")

Answer 1

You should probably understand how to use classes, but here is an example on how to use classes with your given code.

from tkinter import *

class TrafficLights:

    def value(self):

        root = Tk()

        frame = Frame(root)
        frame.pack()

        self.color = StringVar()

        radio_red = Radiobutton(frame, text="Red", bg="red", variable= self.color, value="R", command= self.on_RadioChange)
        radio_red.grid(row=10, column=1)

        radio_yellow = Radiobutton(frame, text="Yellow", bg="yellow", variable= self.color, value="Y", command= self.on_RadioChange)               
        radio_yellow.grid(row = 10, column = 2)

        radio_green = Radiobutton(frame, text="Green", bg="green", variable= self.color, value="G", command= self.on_RadioChange)
        radio_green.grid(row = 10, column = 3)

        self.canvas = Canvas(root, width=450, height=300, bg="white")
        self.canvas.pack()

        self.oval_red = self.canvas.create_oval(10, 10, 110, 110, fill="white")
        self.oval_yellow = self.canvas.create_oval(120, 10, 220, 110, fill="white")
        self.oval_green = self.canvas.create_oval(230, 10, 330, 110, fill="white")

        self.color.set('R')
        self.canvas.itemconfig(self.oval_red, fill="red")
        
        root.mainloop()

    def on_RadioChange(self):
        color = self.color.get()

        if color == 'R':
            self.canvas.itemconfig(self.oval_red, fill="red")
            self.canvas.itemconfig(self.oval_yellow, fill="white")
            self.canvas.itemconfig(self.oval_green, fill="white")
        elif color == 'Y':
            self.canvas.itemconfig(self.oval_red, fill="white")
            self.canvas.itemconfig(self.oval_yellow, fill="yellow")
            self.canvas.itemconfig(self.oval_green, fill="white")
        elif color == 'G':
            self.canvas.itemconfig(self.oval_red, fill="white")
            self.canvas.itemconfig(self.oval_yellow, fill="white")
            self.canvas.itemconfig(self.oval_green, fill="green")

a = TrafficLights()
a.value()

The main mistake was that you were not using self and did not call the method value() . So I fixed all those. So if you dont want to call value() then you would use change def value(self) with def __init__(self): so that now you dont have to call a.value() . I recommend you study more about OOP before proceeding to classes with python and tkinter.

UPDATE:

There is nothing much wrong, just rearrrange the code and change the color inside function to colors or something else, completed code would be:

from tkinter import *

root = Tk()

def on_RadioChange():
        colors = color.get()

        if colors == 'R':
            canvas.itemconfig('oval_red', fill="red")
            canvas.itemconfig('oval_yellow', fill="white")
            canvas.itemconfig('oval_green', fill="white")
        elif colors == 'Y':
            canvas.itemconfig('oval_red', fill="white")
            canvas.itemconfig('oval_yellow', fill="yellow")
            canvas.itemconfig('oval_green', fill="white")
        elif colors == 'G':
            canvas.itemconfig('oval_red', fill="white")
            canvas.itemconfig('oval_yellow', fill="white")
            canvas.itemconfig('oval_green', fill="green")

frame = Frame(root)
frame.pack()

color = StringVar()

radio_red = Radiobutton(frame, text="Red", bg="red", variable=color, value="R", command=on_RadioChange)
radio_red.grid(row=10, column=1)

radio_yellow = Radiobutton(frame, text="Yellow", bg="yellow", variable=color, value="Y", command=on_RadioChange)               
radio_yellow.grid(row = 10, column = 2)

radio_green = Radiobutton(frame, text="Green", bg="green", variable=color, value="G", command=on_RadioChange)
radio_green.grid(row = 10, column = 3)

canvas = Canvas(root, width=450, height=300, bg="white")
canvas.pack()

canvas.create_oval(10, 10, 110, 110, fill="white",tag='oval_red')
canvas.create_oval(120, 10, 220, 110, fill="white",tag='oval_yellow')
canvas.create_oval(230, 10, 330, 110, fill="white",tag='oval_green')

color.set('R')
canvas.itemconfig('oval_red', fill="red")
    
root.mainloop()

Why changing color to colors ? When your using color your actually referencing to color with color , which will raise an UnboundLocalError: local variable 'color' referenced before assignment (since its inside of function?), so to get rid of this, just rename(only in this case). Is this the best way of doing this? I dont think so, there are some useless variables that you could get rid of here.