There is a way to shot multiple times a Sprite (pygame) before kill it from a group?

Question

in a space invaders like game made with pygame, i'm trying to shot 2 times the enemies before kill them, but the result is that Sprite doesn't take care of how many shot each enemy gets, but kills enemies quite random (for example after 2 shots kills another enemy which is not shooted). There is a way to do it? I post part of my code.

all_sprites = pygame.sprite.Group()
bullets = pygame.sprite.Group()
aliens = pygame.sprite.Group()



class Alien(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()

        #self.alieno = pygame.sprite.Sprite(all_sprites, aliens)
        self.image = surf_alien
        self.rect = self.image.get_rect()
        self.alieno_mask = pygame.mask.from_surface(self.image)
        self.energy = 2

    def update(self):
        self.rect.top += 2

#alien.energy = 10
#alien=alien(10)



spr_ship = pygame.sprite.Sprite(all_sprites)
spr_ship.image = surf_ship
spr_ship.rect = spr_ship.image.get_rect()
spr_ship_mask = pygame.mask.from_surface(spr_ship.image)
spr_ship.rect.topleft = (320,500)


#energy=10

vel_ship=[5,5]

pressed = None
pausa = 0




# --- Inizio del gioco
mm.play(-1)
pygame.time.set_timer(USEREVENT, random.randrange(200, 2501))
# --- Ciclo principale
done = False
while not done:

    # --- Ciclo degli eventi
    for ev in pygame.event.get():
        if ev.type == pygame.QUIT:
            done = True

        elif ev.type == KEYDOWN and ev.key == K_p:
            pausa = 1
            mm.stop()
            while pausa == 1:
                clock.tick(1)
                for ev in pygame.event.get():
                    if ev.type == KEYDOWN and ev.key == K_p:
                        pausa = 0
                        mm.play(-1)

        elif ev.type == USEREVENT:
            pygame.time.set_timer(USEREVENT, random.randrange(200, 2501))
            alien = Alien()
            all_sprites.add(alien)
            aliens.add(alien)
            alien.rect.bottom = -10
            alien.rect.x = random.randrange(screen.get_width()-alien.rect.width +1)


        elif ev.type == KEYDOWN and (ev.key == K_LEFT or ev.key == K_RIGHT):
            pressed = ev.key
            #print(pressed)
        elif ev.type == KEYUP and (ev.key == K_LEFT or ev.key == K_RIGHT):          
            pressed = None

        elif ev.type == KEYDOWN and ev.key == K_SPACE:            
            if len(bullets) < 5:
                sound_laser.play()
                bullet = pygame.sprite.Sprite(all_sprites, bullets)
                bullet.image = surf_bullet
                bullet.rect = surf_bullet.get_rect()
                bullet.rect.midbottom = spr_ship.rect.midtop
                bullet_mask = pygame.mask.from_surface(bullet.image)



        elif ev.type == MOUSEMOTION:
            spr_ship.rect.centerx = ev.pos[0]

    # --- Logica del gioco
    all_sprites.update()
    for bullet in bullets:
        bullet.rect.bottom -= 5
        if bullet.rect.bottom < 0:
            bullet.kill()

    for alien in aliens:
        #alien.rect.top += 2
        if alien.rect.top > screen.get_height():
            alien.kill()



        collisioni = pygame.sprite.groupcollide(bullets, aliens, True, False, pygame.sprite.collide_mask)#pygame.sprite.collide_mask
        for i in collisioni:
            sound_expl.play()
            alien.energy-=1            

            if alien.energy<1:
                alien.kill()         

    if pygame.sprite.spritecollide(spr_ship, aliens, True, pygame.sprite.collide_mask):
        sound_end.play()
        pygame.mixer.music.stop()
        #pygame.time.wait(2000)
        while pygame.mixer.get_busy():
            clock.tick(30)
        done = True

    if pressed == K_LEFT and spr_ship.rect.centerx > 0:
        spr_ship.rect.centerx -= vel_ship[0]
    elif pressed == K_RIGHT and spr_ship.rect.centerx < screen.get_width():
        spr_ship.rect.centerx += vel_ship[0]

    # --- Aggiornamento dello schermo
    screen.blit(surf_back,(0,0))
    all_sprites.draw(screen)

    pygame.display.flip()

    clock.tick(30)

# --- Uscita
pygame.quit()
sys.exit()

Answer 1

Your code looks mostly ok. Except that the collision which was previously handling a single alien, is now re-processing the group.

for alien in aliens:
    if alien.rect.top > screen.get_height():
        alien.kill()

    collisioni = pygame.sprite.groupcollide(bullets, aliens, True, False, pygame.sprite.collide_mask)#pygame.sprite.collide_mask
    for i in collisioni:
        sound_expl.play()
        alien.energy-=1            
        if alien.energy<1:
            alien.kill()    

The code already knows which alien it's dealing with, but the groupcollide re-compares all aliens. Perhaps use pygame.sprite.spritecollide() with just the alien instead:

for alien in aliens:
    if alien.rect.top > screen.get_height():
        alien.kill()
    else:
        collisioni = pygame.sprite.spritecollide( alien, bullets, True, pygame.sprite.collide_mask)
        if ( len( collisioni )  > 0 ):
            # there was a collision between this alien and at least one bullet(s)
            sound_expl.play()
            alien.energy -= 1            
            if ( alien.energy < 1 ):
                alien.kill()