Question

好的所以我有一个程序会随机生成一些元组并将它们添加到列表中以用于制作位图图像。问题是我一直收到错误：

Traceback (most recent call last):   File "/Users/Chill/Desktop/Untitled.py", line 27, in <module>
    nextPixel((pixelList[-1])[0], (pixelList[-1])[1], t,)   File "/Users/Chill/Desktop/Untitled.py", line 23, in nextPixel
    if (i, j) not in pixelList: UnboundLocalError: local variable 'pixelList' referenced before assignment [Finished in 0.078s]

以下是代码：

from random import randint
from PIL import Image

startPixel = (0, 0)
pixelList = [startPixel]
print(pixelList[-1])
print(pixelList[-1][0])
i = j = 0
#Replace 0 with timestamp for seed
t = 0


def nextPixel(i, j, t):
    #Random from seed
    iNew = i + randint(0, 2)
    #Random from -seed
    jNew = j + randint(0, 2)
    if iNew == jNew:
        jNew = (jNew + 1) % 2
    iNew -= 1
    jNew -= 1
    #Checks pixel created does not already exist in the list
    if (iNew, jNew) not in pixelList:
        pixelList += (iNew, jNew)

while pixelList[-1][0] < 255:
    nextPixel((pixelList[-1])[0], (pixelList[-1])[1], t)

有什么建议吗？

Answer 1

似乎pixelList是一个元组列表，nextPixel函数意味着向它添加一个新元组。但是，行：

    pixelList += (iNew, jNew)

实际上是在尝试连接新元组和列表。这不起作用，因为增强的分配会将pixelList视为本地变量（不存在，导致错误）。

您需要做的是：

    pixelList.append((iNew, jNew))

Python函数无法识别全局列表

1 个答案: