CODEWITHSUNDEEP
pythonrandompygamerange
thomastaylor
thomastaylor

Reputation: 187

Converting Range Values to Integers

I'm developing a game in pygame where enemy ships will begin off screen then move vertically on the Y-axis towards the player.

However, I'm having a bit of trouble accessing the location of the enemy since it's all relative to a range. I'm not exactly too sure of how to explain it, but here's what I have for the Enemy Class:

class EnemyActive(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        enemy_img_list = ['enemyshipone.png', 'enemyshiptwo.png',
                      'enemyshipthree.png','enemyshipfour.png']
        enemy_img = random.choice(enemy_img_list)
        self.image = pygame.image.load(enemy_img)
        self.rect = self.image.get_rect()
        self.rect.x = random.randrange(0,400)
        self.rect.y = random.randrange(-200,-10)
        self.speed = random.randrange(1,3)

    def update(self):
        self.rect.y += self.speed

    def getCoord(self):
        return (self.rect.x, self.rect.y)

So, when I try to access the position using another function, which takes in an (x,y) coordinate:

particle_list = particles.create_particles(particle_list,enemy.getCoord())

It comes back with an error stating:

numbers = range(-5, -1) + range(1, 5)

TypeError: unsupported operand type(s) for +: 'range' and 'range'

I'm not going to lie and say that I fully understand the error, but I do see logic behind the reasoning for it. How can I actually get my 'getCoord' function to send the appropriate coordinates?

Upvotes: 1

Views: 686

Answers (1)

Efron Licht
Efron Licht

Reputation: 498

In python 3, range is an lazy sequence, not a list. That is, it produces the values one at a time like a generator(lazy), when asked for, rather than storing them all in memory at once (eageR).

You can't add ranges together because they don't have the method for + defined. list does: it concatenates.

We can convert range to a list by calling the list class on it. I.e, list(range(1, 5)).

You can either construct two lists and then concatenate them with +, or you can chain together the generators and then create a single list. This is considered better style since it avoids creating an intermediate list.

Eg:

from itertools import chain
my_list = list(chain(range(-5, -1), range(1, 5)))

Upvotes: 3

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