IndexError：列表索引超出範圍

Question

我一直在嘗試創建程序生成的地下城，如this article所示。但是這對我來說理解這種算法的工作有點難。相反，我一直在使用this作爲指導，至少了解房間的位置。本文中使用的程序是用Java編寫的，因此我對「現實」做了一些修改，並嘗試在Python 3.5中模擬相同的結果。

我的代碼如下：

from random import randint 


class Room: 

    """docstring for Room""" 

    def __init__(self, x, y, w, h): 
     """[summary] 

     [description] 

     Arguments: 
       x {int} -- bottom-left horizontal anchorpoint of the room 
       y {int} -- bottom-left vertical anchor point of the room 
       w {int} -- width of the room 
       h {int} -- height of the room 
     """ 
     self.x1 = x 
     self.x2 = x + w 
     self.y1 = y 
     self.y2 = y + h 
     self.w = w 
     self.h = h 
     self.center = ((self.x1 + self.x2)/2, (self.y1 + self.y2)/2) 

    def intersects(self, room): 
     """[summary] 

     Verifies if the rooms overlap 

     Arguments: 
       room {Room} -- a room object 
     """ 
     return(self.x1 <= room.x2 and self.x2 >= room.x1 and \ 
       self.y1 <= room.y2 and self.y2 >= room.y1) 

    def __str__(self): 
     room_info = ("Coords: (" + str(self.x1) + ", " + str(self.y1) + 
        ") | (" + str(self.x2) + ", " + str(self.y2) + ")\n") 
     room_info += ("Center: " + str(self.center) + "\n") 
     return(room_info) 

MIN_ROOM_SIZE = 10 
MAX_ROOM_SIZE = 20 
MAP_WIDTH = 400 
MAP_HEIGHT = 200 
MAX_NUMBER_ROOMS = 20 

dungeon_map = [[None] * MAP_WIDTH for i in range(MAP_HEIGHT)] 
# print(dungeon_map) 


def crave_room(room): 
    """[summary] 

    "saves" a room in the dungeon map by making everything inside it's limits 1 

    Arguments: 
      room {Room} -- the room to crave in the dungeon map 
    """ 
    for x in xrange(min(room.x1, room.x2), max(room.x1, room.x2) + 1): 
     for y in xrange(min(room.y1, room.y2), max(room.y1, room.y2) + 1): 
      print(x, y) # debug 
      dungeon_map[x][y] = 1 
    print("Done") # dungeon 


def place_rooms(): 

    rooms = [] 

    for i in xrange(0, MAX_NUMBER_ROOMS): 
     w = MIN_ROOM_SIZE + randint(0, MAX_ROOM_SIZE - MIN_ROOM_SIZE + 1) 
     h = MIN_ROOM_SIZE + randint(0, MAX_ROOM_SIZE - MIN_ROOM_SIZE + 1) 
     x = randint(0, MAP_WIDTH - w) + 1 
     y = randint(0, MAP_HEIGHT - h) + 1 

     new_room = Room(x, y, w, h) 
     fail = False 
     for other_room in rooms: 
      if new_room.intersects(other_room): 
       fail = True 
       break 
     if not fail: 
      print(new_room) 
      crave_room(new_room) # WIP 
      new_center = new_room.center 
      # rooms.append(new_room) 
      if len(rooms) != 0: 
       prev_center = rooms[len(rooms) - 1].center 

       if(randint(0, 1) == 1): 
        h_corridor(prev_center[0], new_center[0], prev_center[1]) 
        v_corridor(prev_center[1], new_center[1], prev_center[0]) 
       else: 
        v_corridor(prev_center[1], new_center[1], prev_center[0]) 
        h_corridor(prev_center[0], new_center[0], prev_center[1]) 
     if not fail: 
      rooms.append(new_room) 
    for room in rooms: 
     print(room) 


def h_corridor(x1, x2, y): 
    for x in xrange(min(x1, x2), max(x1, x2) + 1): 
     dungeon_map[x][y] = 1 


def v_corridor(y1, y2, x): 
    for y in xrange(min(y1, y2), max(y1, y2) + 1): 
     dungeon_map[x][y] = 1 

place_rooms() 

但每當我運行它，我得到以下錯誤：

Traceback (most recent call last): 
    File "/home/user/dungeon.py", line 114, in <module> 
    place_rooms() 
    File "/home/user/dungeon.py", line 87, in place_rooms 
    crave_room(new_room) 
    File "/home/user/dungeon.py", line 65, in crave_room 
    dungeon_map[x][y] = 1 
IndexError: list index out of range 

對於我從我的代碼瞭解，crave_room功能應能正常工作，因爲我使用的是min和max函數。並且由於h_corridor和v_corridor函數以類似的方式工作它們呈現相同類型的問題。

我不確定是否因爲使用矩陣作爲原始文章中使用的畫布的替代物而發生問題。我懷疑本地/全球變量問題，但我不認爲這是問題所在。恐怕我犯了一個非常愚蠢的錯誤，沒有看到它。

任何有關更好的數據結構使用的代碼改進技巧或建議都是值得歡迎的，如果有人有這個問題，最好在Python上更清晰/更簡單的文章，我在這裏看到很多相關的帖子，但我仍然有點失落。

感謝您的任何幫助。 ：d

Answer 1

你有你的dungeon_map正確聲明：

dungeon_map = [[None] * MAP_WIDTH] * MAP_HEIGHT 

正確的方法應該是：

dungeon_map = [[None] * MAP_HEIGHT] * MAP_WIDTH 

現在你做到這一點，讓我們來看看第二，更嚴重的問題。讓我們在更小的規模（小圖）的實驗：

MAP_WIDTH = 4 
MAP_HEIGHT = 2 
dungeon_map = [[None] * MAP_HEIGHT] * MAP_WIDTH 

print('\nBefore Assignment:') 
print(dungeon_map) 

dungeon_map[2][1] = 'y' 

print('\nAfter Assignment:') 
print(dungeon_map) 

在這個實驗中，我們創建了一個4列×2行矩陣，我們改變一個單元格的值，所以讓我們來看看輸出：

Before Assignment: 
[[None, None], [None, None], [None, None], [None, None]] 

After Assignment: 
[[None, 'y'], [None, 'y'], [None, 'y'], [None, 'y']] 

這是怎麼回事？基本上，你聲明相同的清單，MAP_WIDTH次。下面的報關行是方便和聰明，但不正確的：

dungeon_map = [[None] * MAP_HEIGHT] * MAP_WIDTH 

正確的方法來聲明這樣一個矩陣是：

dungeon_map = [[None for x in range(MAP_HEIGHT)] for y in range(MAP_WIDTH)]