python出现AttirbuteError:'Group' object has no attribute 'rect'?

Question

1.按照《python编程——从入门到实践》里的“外星人入侵”游戏编写的程序，生成外星人和射击部分完全没问题，到设计外星人与飞船碰撞的模块时就出现了如标题的提示，已经对照过好几遍程序没有问题，不知道哪里出了错

'Group' object has no attribute 'rect'

下面是具体代码：
主程序 alien_invasion.py

import pygame
from pygame.sprite import Group
from game_stats import GameStats

from settings import Settings
from ship import Ship
import game_functions as gf

def run_game():
    ##初始化pygame、设置和屏幕对象
    pygame.display.init()
    ai_settings = Settings()

    screen = pygame.display.set_mode(
        (ai_settings.screen_width, ai_settings.screen_height))
    pygame.display.set_caption("Alien Invasion")

    #创建一个用于存储游戏统计信息的实例
    stats = GameStats(ai_settings)


    #创建一艘飞船、一个子弹编组和一个外星人编组


    #创建一艘飞船
    ship = Ship(ai_settings, screen)
    #创建一个用于存储子弹的编组
    bullets = Group()
    aliens = Group()

    #创建外星人裙
    gf.create_fleet(ai_settings, screen, aliens, ship)


    

    #开始游戏的主循环
    while True:
        gf.check_events(ai_settings, screen, ship, bullets)
        if stats.game_active:
            ship.update()
            gf.update_bullets(ai_settings, screen, ship, aliens, bullets)
            gf.update_aliens(ai_settings, stats, screen, ship, aliens, bullets)
        
        gf.update_screen(ai_settings, screen, ship, aliens, bullets)


        

run_game()

    ##

game_function.py

import sys
import pygame

from alien import Alien
from bullet import Bullet
from time import sleep

def check_keydown_events(event, ai_settings, screen, ship, bullets):
    """响应按键"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True

    if event.key == pygame.K_LEFT:
        ship.moving_left = True


    elif event.key == pygame.K_SPACE:
        #创建一颗子弹，并将其加入到编组bullets中
        fire_bullet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_q:
        sys.exit()

def fire_bullet(ai_settings, screen, ship, bullets):
    """如果还没有到达限制，就发射一颗子弹"""
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)
    

def check_keyup_events(event, ship):
    """响应松开"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False

    if event.key == pygame.K_LEFT:
        ship.moving_left = False

    

def check_events(ai_settings, screen, ship, bullets):
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event, ai_settings, screen, ship, bullets)

        elif event.type == pygame.KEYUP:
            check_keyup_events(event, ship)




def update_screen(ai_settings, screen, ship, aliens, bullets):
    """更新屏幕上的图像，并切换到新屏幕"""
    #每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)

    #在飞船和外星人后面重绘所有子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)

    
    #让最近绘制的屏幕可见
    pygame.display.flip()

def update_bullets(ai_settings,  screen, ship, aliens, bullets):
    """更新子弹的位置，并删除已消失的子弹"""
    #更新子弹的位置
    bullets.update()

    #删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)

    check_bullet_alien_collisions(ai_settings, screen, ship, aliens, bullets)


def check_bullet_alien_collisions(ai_settings, screen, ship, aliens, bullets):
    """响应子弹和外星人的碰撞"""
    #删除发生碰撞的外星人
    collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)

    if len(aliens) == 0:
        #删除现有的子弹并新建一群外星人
        bullets.empty()
        create_fleet(ai_settings, screen, ship, aliens)

def create_fleet(ai_settings, screen, aliens, ship):
    """创建外星人裙"""
    #创建一个外星人，并计算一行可容纳多少个外星人
    alien = Alien(ai_settings, screen)
    number_alien_x = get_number_aliens_x(ai_settings, alien.rect.width)
    number_rows = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)
    
    #创建第一行外星人
    for row_number in range(number_rows):
        for alien_number in range(number_alien_x):
            #创建一个外星人并将其加入当前行
            create_alien(ai_settings, screen, aliens, alien_number, row_number)

def get_number_aliens_x(ai_settings, alien_width):
    """计算每行可容纳多少个外星人"""
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_alien_x = int(available_space_x / (2 * alien_width))
    return number_alien_x
    
def create_alien(ai_settings, screen, aliens, alien_number, row_number):
    """创建一个外星人并将其放在当前行"""
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
    aliens.add(alien)    

def get_number_rows(ai_settings, ship_height, alien_height):
    """计算屏幕可容纳多少行外星人"""
    available_space_y = (ai_settings.screen_height - 
                                (3 * alien_height) - ship_height)
    number_rows = int(available_space_y / (2 * alien_height))
    return number_rows
    
def check_fleet_edgs(ai_settings, aliens):
    """有外星人到达边缘时采取相应的措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break

def change_fleet_direction(ai_settings, aliens):
    """将整群外星人下移， 并改变他们的方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1

def ship_hit(ai_settings, stats, screen, ship, aliens, bullets):
    """响应被外星人撞到的飞船"""
    #将ships_left减1
    if stats.ships_left > 0:
        stats.ships_left -= 1

        #晴空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()

        #创建一群新的外星人，并将飞船放在屏幕底端中央
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()

        #暂停
        sleep(0.5)
    else:
        stats.game_active = False




def check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets):
    """检查是否有外星人到达了屏幕底端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            #像飞船被撞倒一样进行处理
            ship_hit(ai_settings, stats, screen, ship, aliens, bullets)
            break

def update_aliens(ai_settings, stats, screen, ship, aliens, bullets):
    """检查是否有娃星人位于屏幕边缘，并更新整群外星人的位置"""
    check_fleet_edgs(ai_settings, aliens)
    aliens.update()

    #检测外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship, aliens):
        ship_hit(ai_settings, stats, screen, ship, aliens, bullets)

    #检查是否有外星人到达屏幕底端
    check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets)

ship.py

import pygame

class Ship():

    def __init__(self, ai_settings, screen):
        """初始化飞船并设置其初始位置"""
        self.screen = screen
        self.ai_settings = ai_settings

        #加载飞船图像并获取其外接矩形
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        #将每艘新飞船放在屏幕底部中央
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom

        #在飞船的属性center中存储小数值
        self.center = float(self.rect.centerx)

        #移动标志
        self.moving_right = False
        self.moving_left = False
        

    def update(self):
        """根据移动标志调整飞船的位置"""
        #更新飞船的center值，而不是rect
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.center += self.ai_settings.ship_speed_factor

        if self.moving_left and self.rect.left > 0:
            self.center -= self.ai_settings.ship_speed_factor

        

        #根据self.center更新rect对象
        self.rect.centerx = self.center

    def blitme(self):
        """在指定位置绘制飞船"""
        self.screen.blit(self.image, self.rect)

    def center_ship(self):
        """让飞船在屏幕上居中"""
        self.center = self.screen_rect.centerx

Traceback (most recent call last):
File "/Users/Eahon/Desktop/Python_work/u5916u661fu4ebau5165u4fb5/alien_invasion.py", line 50, in <module>

run_game()

File "/Users/Eahon/Desktop/Python_work/u5916u661fu4ebau5165u4fb5/alien_invasion.py", line 43, in run_game

gf.update_aliens(ai_settings, stats, screen, ship, aliens, bullets)

File "/Users/Eahon/Desktop/Python_work/u5916u661fu4ebau5165u4fb5/game_functions.py", line 179, in update_aliens

ship_hit(ai_settings, stats, screen, ship, aliens, bullets)

File "/Users/Eahon/Desktop/Python_work/u5916u661fu4ebau5165u4fb5/game_functions.py", line 152, in ship_hit

create_fleet(ai_settings, screen, ship, aliens)

File "/Users/Eahon/Desktop/Python_work/u5916u661fu4ebau5165u4fb5/game_functions.py", line 98, in create_fleet

number_rows = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)

AttributeError: 'Group' object has no attribute 'rect'
[Finished in 7.4s with exit code 1]
[cmd: ['/usr/local/bin/python3', '-u', '/Users/Eahon/Desktop/Python_work/外星人入侵/alien_invasion.py']]
[dir: /Users/Eahon/Desktop/Python_work/外星人入侵]
[path: /Library/Frameworks/Python.framework/Versions/3.6/bin:/Users/Eahon/Library/Enthought/Canopy_64bit/User/bin:/Library/Frameworks/Python.framework/Versions/2.7/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin]

Answer 1

调用：

create_fleet(ai_settings, screen, ship, aliens)

定义：

def create_fleet(ai_settings, screen, aliens, ship):

ship和aliens参数位置写反了