python - 如何在 random.randrange 中使用负数

Question

我正在尝试制作一个游戏，在这个游戏中我想在 0 到 -100 之间的随机 Y 位置上制作 100 个对象。

但是当我尝试random.randrange(0, -100)时，它返回一条错误消息:

Traceback (most recent call last):
  File "main.py", line 144, in <module>
    main();
  File "main.py", line 30, in main
    setGlobalValues();
  File "main.py", line 23, in setGlobalValues
    food = Food();
  File "main.py", line 92, in __init__
    self.y = random.randrange(0, -100);
  File "C:\Users\sidna\AppData\Local\Programs\Python\Python36-32\lib\random.py", line 198, in randrange
    raise ValueError("empty range for randrange() (%d,%d, %d)" % (istart, istop, width))
ValueError: empty range for randrange() (0,-100, -100)

完整代码如下:

Python

# IMPORTS
import pygame, random;

# GLOBALS
global screen, displayW, displayH;
global clock, FPS;
global end, food, player;

# SETGLOBALVALUES
def setGlobalValues():
    global screen, displayW, displayH;
    global clock, FPS;
    global end, food, player;

    displayW = 800;
    displayH = 600;
    screen = pygame.display.set_mode((displayW, displayH));

    clock = pygame.time.Clock();
    FPS = 60;

    end = False;
    food = Food();
    player = Player();

# MAIN
def main():
    pygame.init();

    setGlobalValues();
    setup();
    gameLoop();
    quitGame();

# GAMELOOP
def gameLoop():
    global end, player;

    while(not end):
        for event in pygame.event.get():
            # ONCLICK QUIT
            if(event.type == pygame.QUIT):
                end = True;

            # KEYDOWN
            if(event.type == pygame.KEYDOWN):
                if(event.key == pygame.K_LEFT):
                    player.velX -= 1;
                if(event.key == pygame.K_RIGHT):
                    player.velX += 1;

            # KEYUP
            if(event.type == pygame.KEYUP):
                if(event.key == pygame.K_LEFT):
                    player.velX = 0;
                if(event.key == pygame.K_RIGHT):
                    player.velX = 0;

        draw();
        animate();


# DRAW
def draw():
    global screen, food, player;

    # fill background
    screen.fill((255, 255, 255));

    food.draw();

    # update
    pygame.display.update();

# ANIMATE
def animate():
    global food, player;

    food.animate();
    player.animate();

# COLLISION
def collision():
    pass;

# CLASSES
class Food():
    def __init__(self, x=0, y=0, w=0, h=0, velY=0, color=()):
        global displayW;

        self.x = random.randrange(0, displayW);
        self.y = random.randrange(0, -100);
        self.w = 20;
        self.h = 20;
        self.velY = 0.7;
        self.color = (255, 0, 0);

    def draw(self):
        global screen;

        for amount in range(100):
            pygame.draw.rect(screen, self.color, (self.x, self.y, self.w, self.h));

    def animate(self):
        self.y += self.velY;

    def collision(self):
        global displayW, displayH;

        pass;

class Player():
    def __init__(self, x=0, y=0, velX=0, velY=0, w=0, h=0, color=()):
        global displayW, displayH;

        self.w = 20;
        self.h = 20;
        self.x = displayW / 2 - self.w / 2;
        self.y = displayH - 100;
        self.velX = 0;
        self.velY = 0;
        self.color = (0, 0, 0);

    def draw(self):
        global screen;

        pygame.draw.ellipse(screen, self.color, (self.x, self.y, self.w, self.h));

    def animate(self):
        self.x += self.velX;
        self.y += self.velY;

# SETUP
def setup():
    pygame.display.set_caption("Food Catcher");

# QUIT GAME
def quitGame():
    pygame.quit();
    quit();

# CALL MAIN
if(__name__ == "__main__"):
    main();

Answer 1

smaller number should be the first argument (如果您使用多个参数):

import random
random.randrange(-100, 1)

不包含第二个参数，因此如果您希望 0 作为可能的结果，则需要将其设置为 1。

<小时/>

但是，如果您实际上没有使用 step 参数，那么还有 random.randint :

random.randint(-100, 0)  # randint includes the "stop"!