tkinter: displaying a square grid - user-interface

Question

I'm trying to use tkinter to periodically refresh a square grid. Each square in the grid is painted a certain color (say obtained from a given function); in the center of each square, a smaller circle is drawn (the color is also obtained from a function).
If I have to do it from scratch, perhaps there's an example or a standard recipe I can use?

Answer 1

Here's a quick hack showing how to draw a grid of rectangles and circles, and how to update the display once a second. If you've never programmed in tk before, it uses concepts that are no doubt foreign to you. You'll need to read up on canvas object ids and tags, as well as what the after command does.
import Tkinter as tk
import random
class App(tk.Tk):
def __init__(self, *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
self.canvas = tk.Canvas(self, width=500, height=500, borderwidth=0, highlightthickness=0)
self.canvas.pack(side="top", fill="both", expand="true")
self.rows = 100
self.columns = 100
self.cellwidth = 25
self.cellheight = 25
self.rect = {}
self.oval = {}
for column in range(20):
for row in range(20):
x1 = column*self.cellwidth
y1 = row * self.cellheight
x2 = x1 + self.cellwidth
y2 = y1 + self.cellheight
self.rect[row,column] = self.canvas.create_rectangle(x1,y1,x2,y2, fill="blue", tags="rect")
self.oval[row,column] = self.canvas.create_oval(x1+2,y1+2,x2-2,y2-2, fill="blue", tags="oval")
self.redraw(1000)
def redraw(self, delay):
self.canvas.itemconfig("rect", fill="blue")
self.canvas.itemconfig("oval", fill="blue")
for i in range(10):
row = random.randint(0,19)
col = random.randint(0,19)
item_id = self.oval[row,col]
self.canvas.itemconfig(item_id, fill="green")
self.after(delay, lambda: self.redraw(delay))
if __name__ == "__main__":
app = App()
app.mainloop()