Why am I getting KeyError: 0

Question

我正在尝试编写 Conway 的 Game of Life。据我所知，程序应该是完整的，但是当我运行它时，我得到 KeyError: 0，据我所知，这意味着引用了一个不存在的字典键。字典 (cell_dict) 包含构成 dead/alive 单元格的 20x20 网格的 tkinter 按钮。

完整代码如下：

#imports
import tkinter
import random

#functions
def step(): #updates the status of each cell
    for i in range(0,20): # runs through each cell to check the number of living neighbors
        for j in range(0,20):

            cell = cell_dict[i][j] #key error happens here
            pop = 0

            for n in range(-1,2): #checks each neighbor and tracks the number of alive ones
                for m in range(-1,2):
                    if i+n in range(0,20) and j+m in range(0,20):
                        if n != 0 or m != 0:
                            cell_neighbor = cell_dict[i+n][j+m]
                            if cell_neighbor['bg'] == "yellow":
                                pop += 1

            if cell['bg'] == "yellow" and (pop == 2 or pop == 3): #primes the new status for the cell
                cell['fg'] = "yellow"
            elif cell['bg'] == "black" and pop == 3:
                cell['fg'] = "yellow"
            else:
                cell['fg'] = "black"

    for i in range(0,20): #updates the status of each cell
        for j in range(0,20):
            cell = cell_dict[i][j]
            if cell['fg'] == "black":
                cell['bg'] = "black"
            elif cell['fg'] == "yellow":
                cell['bg'] = "yellow"

    window.after(1000,step) #repeats the process every second

#gui
window = tkinter.Tk()

cell_dict = {} #primes the dictionary

for i in range(0,400): #creates all the cells
    cell = tkinter.Button(fg = "white", bg = "white", height = 1, width = 2)

    r = random.randrange(0,2) #randomly determines if the cell will be initially dead or alive

    if r == 0:
        cell['bg'] = "black" #dead
    elif r == 1:
        cell['bg'] = "yellow" #alive

    cell.grid(row = int(i/20)%20, column = i%20) #packs the cell into the grid

    cell_dict[(int(i/20)%20,i%20)] = cell #stores the cell in the dictionary

#mainloop
step()
window.mainloop()

我注意到一旦弹出键错误，i = 399 并且 j 未定义。因此，代码似乎以某种方式跳过了“for i in range(0,2): for j in range(0,20):”。我是编码新手，所以我不确定哪里出错了。

Answer 1

你没有包括回溯，所以这只是一个有根据的猜测，但我怀疑你的问题写得更清楚：

cell_dict = {}
for i in range(0,400):
    cell_dict[(int(i/20)%20,i%20)] = None

print(cell_dict)
for i in range(0,20):
    for j in range(0,20):
    cell = cell_dict[i][j]  # key error happens here

事实上，您的密钥确实存在错误。

您的密钥是 cell_dict[(x, y)] -> cell，但您本应拥有 cell_dict[x][y] -> cell:

您可以通过多种方式解决该问题，在循环中分配字典，使用如下所示的 setdefault 或 collections.defaultdict 等

    cell_dict.setdefault(int(i/20)%20, {})[i%20] = None

Answer 2

您似乎将单元格位置存储为两个整数的元组。所以你应该用那个而不是整数来解决cell_dict。

使用 cell_dict[(i, j)] 而不是 cell_dict[i][j]。

Why am I getting KeyError: 0

Why am I getting KeyError: 0

python

keyerror