I am making an "game" that has pathfinding using pygame. I am using Astar algo.

I have a main loop which draws the whole map. In the loop I check for events. If user press "enter" or "space", random start and end are selected, then animation starts and it will try to get from start to end.

My draw function is stupid as hell right now, it works as expected but I feel that I am doing it wrong. It'll draw everything to the end of the animation. I am also detecting events in there as well. What is a better way of implementing the draw function such that it will draw one "step" at a time while checking for events?

animating = False;

while loop:
    check events:
        if not animating:
            # space or enter press will choose random start/end coords              
            if enter_pressed or space_pressed:
                start, end = choose_coords
                route = find_route(start, end)
                draw(start, end, grid, route)
        else:
            # left click == generate an event to block the path
            # right click == user can choose a new destination
            if left_mouse_click:
                gen_event()
                reroute()
            elif right_mouse_click:
                new_end = new_end()
                new_start = current_pos()
                route = find_route(new_start, new_end)
                draw(new_start, new_end, grid, route)


# draw out the grid
def draw(start, end, grid, route_coord):
    # draw the end coords
    color = red;
    pick_image(screen, color, width*end[1],height*end[0]);
    pygame.display.flip();

    # then draw the rest of the route
    for i in range(len(route_coord)):
        # pausing because we want animation
        time.sleep(speed);

        # get the x/y coords
        x,y = route_coord[i];
        event_on = False;

        if grid[x][y] == 2:
            color = green;
        elif grid[x][y] == 3:
            color = blue;

            for event in pygame.event.get():
                if event.type == pygame.MOUSEBUTTONDOWN:
                    if event.button == 3:
                        print "destination change detected, rerouting";
                        # get mouse position, px coords
                        pos = pygame.mouse.get_pos();

                        # get grid coord
                        c = pos[0] // width;
                        r = pos[1] // height;

                        grid[r][c] = 4;
                        end = [r, c];
                    elif event.button == 1:
                        print "user generated event";
                        pos = pygame.mouse.get_pos();

                        # get grid coord
                        c = pos[0] // width;
                        r = pos[1] // height;

                        # mark it as a block for now
                        grid[r][c] = 1;
                        event_on = True;

            if check_events([x,y]) or event_on: # there is an event
                # mark it as a block for now
                grid[y][x] = 1;

                pick_image(screen, event_x, width*y, height*x);
                pygame.display.flip();

                # then find a new route
                new_start = route_coord[i-1];
                marked_grid, route_coord = find_route(new_start, end, grid);

                draw(new_start, end, grid, route_coord);
                return; # just end draw here so it wont throw the "index out of range" error
        elif grid[x][y] == 4:
            color = red;
        pick_image(screen, color, width*y, height*x);
        pygame.display.flip();

    # clear route coord list, otherwise itll just add more unwanted coords
    route_coord_list[:] = [];