Positioning and adding enemies in a pygame 2d scrolling platformer?

Question

I have been trying to create a mario type 2d side scrolling platformer using python and the pygame module. I used tutorials from programarcadegames to code the platforms and player, i just can't figure out how to implement enemies that spawn at a particular x and y coordinate and add them as a collide-able sprite (That "kills" the player in one hit)?

The tutorials code is below:

http://programarcadegames.com/python_examples/show_file.php?file=platform_moving.py

Ive tried creating the basic class for the enemy sprite and making it move in a backwards and forwards motion but positioning it is my main problem.

Here's my code: (The enemy does glitch a bit when the level is scrolled)

class Enemy(pygame.sprite.Sprite):

    def __init__(self):

        super().__init__()

        width = 30
        height = 30
        self.image = pygame.Surface([width, height])
        self.image.fill(BLUE)

        # Set a reference to the image rect.
        self.rect = self.image.get_rect()

        # Set speed vector of player
        self.change_x = random.randint(3, 4)
        self.change_y = 0

    def update(self):

        self.rect.centerx += self.change_x
        if self.rect.right <= 0 or self.rect.left >= 100:
            self.change_x *= -1

Answer 1

for the collision with the player i recommend you something like this:

#in your gameloop
playerEnemyCollision = pygame.sprite.spritecollide(player, enemies, False)

"enemies" needs to be a sprite-group.To create a sprite group:

#outside your gameloop
enemies = pygame.sprite.Group()

To create a new Enemy and add it to the group, just typ:

#outside your gameloop
en = Enemy()
en.rect.x = XX #set your Enemies x-Position
en.rect.y = YY #set your Enemies y-Position
en.add(enemies) #adds the enemy "en" to the sprite-group "enemies"

Now you can check for a collision with:

#in your gameloop
if playerEnemyCollision:
    #your "kill-player-code" goes her
    #Example:
    player.kill()

It is at the most time not such a good idea to change a sprite's location for normal movement outside your "Enemy-Class". I hope i could help you with your question. Twistios