Pygame crashing when enemy spawns

Question

I am making a spaceship game where you control a spaceship and fire bullets to defeat enemies. I have already accomplished the goal where enemies spawn on top of the screen. The problem is, Hundreds of thousands of enemies spawn on top of the screen. I tried using the sleep function from the time module, but that didn't work. Instead, the game crashed right when I ran it! Can anybody help me?

This is my current code:

import pygame
from pygame.locals import *
from random import randint
from time import sleep

pygame.init()
screen = pygame.display.set_mode((800, 500))
screen.fill((255, 255, 255))


class Spaceship(pygame.sprite.Sprite):

    def __init__(self, s, x, y):
        pygame.sprite.Sprite.__init__(self)

        self.screen = s
        self.x, self.y = x, y
        self.image = pygame.image.load("C:/eqodqfe/spaceship.png")
        self.image = pygame.transform.scale(self.image, (175, 175))
        self.rect = self.image.get_rect()
        self.rect.center = (self.x, self.y)

    def update(self):
        self.rect.center = (self.x, self.y)


class Bullet(pygame.sprite.Sprite):

    def __init__(self, s, x, y):
        pygame.sprite.Sprite.__init__(self)

        self.screen = s
        self.x, self.y = x, y
        self.image = pygame.image.load("C:/eqodqfe/bullet.png")
        self.image = pygame.transform.scale(self.image, (100, 100))
        self.rect = self.image.get_rect()
        self.rect.center = (self.x, self.y)

    def update(self):
        self.y -= 5
        self.rect.center = (self.x, self.y)
        if self.y < 0:
            self.kill()


class Enemy(pygame.sprite.Sprite):

    def __init__(self, s, x, y):
        pygame.sprite.Sprite.__init__(self)

        self.screen, self.x, self.y = s, x, y
        self.image = pygame.image.load("C:/eqodqfe/enemy.png")
        self.image = pygame.transform.scale(self.image, (240, 210))
        self.rect = self.image.get_rect()
        self.rect = self.image.get_rect()
        self.rect.center = (self.x, self.y)

    def update(self):
        self.rect.center = (self.x, self.y)


spaceship = Spaceship(screen, 400, 400)

bullets = pygame.sprite.Group()
enemies = pygame.sprite.Group()

clock = pygame.time.Clock()

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        if event.type == MOUSEBUTTONDOWN:
            bullet = Bullet(screen, spaceship.x, spaceship.y - 20)
            bullets.add(bullet)

    bullets.update()

    key = pygame.key.get_pressed()
    amount = 5

    if key[pygame.K_a]:
        spaceship.x -= amount
    elif key[pygame.K_d]:
        spaceship.x += amount
    elif key[pygame.K_w]:
        spaceship.y -= amount
    elif key[pygame.K_s]:
        spaceship.y += amount

    spaceship.update()

    screen.fill((255, 255, 255))

    screen.blit(spaceship.image, spaceship.rect)

    enemy = Enemy(screen, randint(-200, 800), 0)
    enemies.add(enemy)
    sleep(5)

    bullets.draw(screen)
    enemies.draw(screen)

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

Answer 1

Use a timer event to spawn enemies.

In pygame exists a timer event. Use pygame.time.set_timer() to repeatedly create a USEREVENT in the event queue. The time has to be set in milliseconds. e.g.:

enemy_interval = 1000 # 1000 milliseconds == 1 seconds
enemy_event = pygame.USEREVENT + 1
pygame.time.set_timer(enemy_event, enemy_interval)

Create a new enemy when the event occurs:

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        if event.type == MOUSEBUTTONDOWN:
            bullet = Bullet(screen, spaceship.x, spaceship.y - 20)
            bullets.add(bullet)

        if event.type == enemy_event:
            enemy = Enemy(screen, randint(-200, 800), 0)
            enemies.add(enemy)

    # [...]

    # DELETE
    # enemy = Enemy(screen, randint(-200, 800), 0)
    # enemies.add(enemy)
    # sleep(5)

    # [...]