太空侵略者游戏奇怪类型错误：'int'对象不可下标 Python 中的错误

游戏开始运行良好，然后在我杀死3-12个敌人后，它崩溃并给我类型错误："int"对象不可下标错误这是它所说的导致问题的代码行，enemyX[i]+=enemyX_change[i]

我很困惑这个程序是如何完美运行的，直到一定数量的敌人被击中。如果我只是让程序运行而不关机，它就会运行，直到所有的敌人都跑到屏幕底部。

这是的所有代码

import pygame
import random
import math
#pygame.time.Clock(30)
# Initialize the game
pygame.init()
# Screen
screen = pygame.display.set_mode((800, 600))
# background
background = pygame.image.load('background.png')
# Title and icon
pygame.display.set_caption("Space Invaders")
# player
playerImg = pygame.image.load('spaceship.png')
playerX = 370
playerY = 510
playerX_change = 0
# enemy
enemyImg = []
enemyX = []
enemyY = []
enemyX_change = []
enemyY_change = []
num_of_enemies = 6
for i in range(num_of_enemies):
enemyImg.append(pygame.image.load('ufo.png'))
enemyX.append(random.randint(0, 735))
enemyY.append(random.randint(40, 100))
enemyX_change.append(2)
enemyY_change.append(40)
# missile
missileImg = pygame.image.load('missile.png')
missileX = playerX
missileY = 483
missileY_change = 6
missile_state = "ready"
def player(x, y):
screen.blit(playerImg, (x, y))
def enemy(x, y, i):
screen.blit(enemyImg[i], (x, y))
def fire_missile(x, y):
global missile_state
missile_state = "fire"
screen.blit(missileImg, (x + 16, y + 10))
def is_collision(enemyX, enemyY, missileX, missileY):
distance = math.sqrt((math.pow(enemyX - missileX, 2)) + (math.pow(enemyY - missileY, 2)))
if distance < 27:
return True
else:
return False
# Game loop
clock = pygame.time.Clock()
running = True
while running:
clock.tick(60)
screen.fill((0, 0, 0))
# background image
screen.blit(background, (-100, 0))
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
# if keystroke is pressed check what key it is
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_a:
playerX_change = -3
if event.key == pygame.K_d:
playerX_change = +3
if event.key == pygame.K_SPACE:
if missile_state == "ready":
missileX = playerX
missileY = playerY - 27
fire_missile(missileX, missileY)
if event.type == pygame.KEYUP:
if event.key == pygame.K_a or event.key == pygame.K_d:
playerX_change = 0
# spaceship boundary
playerX += playerX_change
if playerX <= 0:
playerX = 0
elif playerX >= 740:
playerX = 740
# enemy movement
for i in range(num_of_enemies):
enemyX[i] += enemyX_change[i]
if enemyX[i] <= 0:
enemyX_change[i] = 2
enemyY[i] += enemyY_change[i]
elif enemyX[i] >= 740:
enemyX_change[i] = -2
enemyY[i] += enemyY_change[i]
collision = is_collision(enemyX[i], enemyY[i], missileX, missileY)
if collision:
missileY = 483
missile_state = "ready"
score += 1
print(score)
enemyX[i] = random.randint(0, 735)
enemyY[i] = random.randint(40, 100)
enemy(enemyX[i], enemyY[i], i)
# missile movement
if missileY < -10:
missileY = 483
missile_state = "ready"
if missile_state is "fire":
fire_missile(missileX, missileY)
missileY -= missileY_change

collision = is_collision(enemyX[i], enemyY[i], missileX, missileY)
if collision:
missileY = 483
missile_state = "ready"
score += 1
print(score)
enemyX = random.randint(0, 735)
enemyY = random.randint(40, 100)
player(playerX, playerY)
pygame.display.update()

谢谢你的帮助，我想不通。