Following with vectors test

import math
import pygame

pygame.init()

screen_width, screen_heigth = 800, 600
rect_width, rect_height = 40, 40
step = 3
ai_step = 2

screen = pygame.display.set_mode((screen_width, screen_heigth))
screen_rect = screen.get_rect()

# The player starts in the top left corner, the AI in the bottom right
player_rect = pygame.Rect(0, 0, rect_width, rect_height)
ai_rect = pygame.Rect(screen_width - rect_width, screen_heigth - rect_height, rect_width, rect_height)

clock = pygame.time.Clock()
running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_q:
                running = False

    pressed_keys = pygame.key.get_pressed()
    # First move the player rect in place (move_ip)
    # clamp makes sure the player doesn't go out of the screen
    # Note: This is not necessarily the fastest (perfomance-wise)
    #       way to do this.
    if pressed_keys[pygame.K_LEFT]:
        player_rect.move_ip(-step, 0)
        player_rect.clamp(screen_rect)
    if pressed_keys[pygame.K_RIGHT]:
        player_rect.move_ip(step, 0)
        player_rect.clamp(screen_rect)
    if pressed_keys[pygame.K_UP]:
        player_rect.move_ip(0, -step)
        player_rect.clamp(screen_rect)
    if pressed_keys[pygame.K_DOWN]:
        player_rect.move_ip(0, step)
        player_rect.clamp(screen_rect)

    vector = (player_rect.center[0] - ai_rect.center[0], player_rect.center[1] - ai_rect.center[1])
    # math.hypot (Hypotenuse) is equivalent to
    # math.sqrt(vector[0] ** 2 + vector[1] ** 2)
    length = math.hypot(*vector)
    normalized = (vector[0] / length, vector[1] / length)

    # Note: you don't have to round this apparently :)
    ai_rect.x += normalized[0] * ai_step
    ai_rect.y += normalized[1] * ai_step

    # Note: the AI will always move slower than the player (with ai_step <= step),
    #       because the player can move 2 * step pixels at once (both horizontally and vertically),
    #       while the AI can move only ai_step pixels.


    screen.fill(pygame.Color("White"))

    pygame.draw.rect(screen, pygame.Color("Blue"), player_rect)
    pygame.draw.rect(screen, pygame.Color("Red"), ai_rect)


    pygame.display.flip()
    clock.tick(60)