print(count) 如何导致列表索引超出范围错误？

Question

我就是瞎混，决定做一个高斯分布的可视化，不知怎的，这个错误恰好存在。我以前从未见过这个错误，最奇怪的是它不会在每次循环运行时都发生。这完全是随机的。有时它会在循环的第一次迭代时出错，有时它根本不会出错。当传递一个 int 时，print() 函数 return 到底怎么会出现索引错误。这是所有代码：

import math
import pygame
import os

wS = 500

n = 50

os.environ["SDL_VIDEO_WINDOW_POS"] = "%d, %d" % (5, 5)

pygame.init()

window = pygame.display.set_mode((wS, wS), 0, 0, 0)
li = [math.floor(random.gauss(350, 20)) for i in range(50)]
lmax = 0
lmin = 1000
off = wS/2

leng = len(li)

for i in range(len(li)):
    if li[i] > lmax:
        lmax = li[i]

xV = wS/n
xV2 = wS/lmax
print(li)

def run():
    global li
    global xV
    global lmax
    global off


    keys = pygame.key.get_pressed()
    count = 0
    p = pygame.PixelArray(window)
    while not keys[pygame.K_ESCAPE] and not keys[pygame.K_SPACE] and count < (leng - 1):
        print(count)
        event = pygame.event.get()
        keys = pygame.key.get_pressed()

        x = int(xV * count)

        y = int(off + ((li[count]/lmax) * off))

        p[x][y] = (255, 255, 255)
        count+=1
    print("done")
    pygame.display.update()
    keys = pygame.key.get_pressed()
    while not keys[pygame.K_ESCAPE] and not keys[pygame.K_SPACE]:
        event = pygame.event.get()
        keys = pygame.key.get_pressed()

run()

错误：

Traceback (most recent call last):
  File "*redacted*", line 58, in <module>
    run()
  File "*redacted*", line 41, in run
    print(count)
IndexError: array index out of range

Answer 1

当您使用 pygame.PixelArray 时，os 事件被阻止。当像素阵列表面被锁定时，pygame.event.get() 和 pygame.key.get_pressed() 都会出现 return 错误。

这是更新后的代码。我从循环中删除了事件。我还添加了对 x,y 坐标的检查，以确保它们在数组内。

import math
import pygame
import os
import random

wS = 500

n = 50

os.environ["SDL_VIDEO_WINDOW_POS"] = "%d, %d" % (5, 5)

pygame.init()

window = pygame.display.set_mode((wS, wS), 0, 0, 0)

li = [math.floor(random.gauss(350, 20)) for i in range(50)]
lmax = 0
lmin = 1000
off = wS/2

leng = len(li)

for i in range(len(li)):
    if li[i] > lmax:
        lmax = li[i]

xV = wS/n
xV2 = wS/lmax
print(li)

def run():
    global li, xV, lmax, off

    count = 0
    p = pygame.PixelArray(window)  # lock surface for drawing

    while count < (leng - 1):
        x = int(xV * count)
        y = int(off + ((li[count]/lmax) * off))
        if x < wS and y < wS: p[x,y] = (255, 255, 255)
        count+=1
        
    p.close()  # unlock surface
        
    print("done")
    pygame.display.update()
    keys = pygame.key.get_pressed()
    while not keys[pygame.K_ESCAPE] and not keys[pygame.K_SPACE]:
        event = pygame.event.get()
        keys = pygame.key.get_pressed()

run()

print(count) 如何导致列表索引超出范围错误？

How is print(count) resulting in a list index out of range error?

python

pygame

index-error