我在 Python shell 上检查了几个例子，它们似乎吐出相同的数字。但是在一个应该对大量数字进行近似的程序中，它们显然会产生不同的结果。
我正在尝试编写一个小程序来模拟物体在矩形平面上的运动。为此，我必须编写一个名为“RectangularRoom”的类，它接受宽度和高度并创建一个网格:
class RectangularRoom(object):
"""
A RectangularRoom represents a rectangular region containing clean or dirty
tiles.
A room has a width and a height and contains (width * height) tiles. At any
particular time, each of these tiles is either clean or dirty.
"""
def __init__(self, width, height):
"""
Initializes a rectangular room with the specified width and height.
Initially, no tiles in the room have been cleaned.
width: an integer > 0
height: an integer > 0
"""
self.width = width
self.height = height
self.room_coordinates = []
for m in range(self.width):
for n in range(self.height):
self.room_coordinates.append((m,n))
self.cleaned = []
def cleanTileAtPosition(self, pos):
"""
Mark the tile under the position POS as cleaned.
Assumes that POS represents a valid position inside this room.
pos: a Position
"""
self.cleaned.append((int(pos.getX()), int(pos.getY())))
def isTileCleaned(self, m, n):
"""
Return True if the tile (m, n) has been cleaned.
Assumes that (m, n) represents a valid tile inside the room.
m: an integer
n: an integer
returns: True if (m, n) is cleaned, False otherwise
"""
assert type (m)== int and type (n) == int
return (m,n) in self.cleaned
def getNumTiles(self):
"""
Return the total number of tiles in the room.
returns: an integer
"""
return self.width*self.height
def getNumCleanedTiles(self):
"""
Return the total number of clean tiles in the room.
returns: an integer
"""
return len(self.cleaned)
def getRandomPosition(self):
"""
Return a random position inside the room.
returns: a Position object.
"""
return Position (random.randrange(0 , self.width), random.randrange(0 , self.height))
def isPositionInRoom(self, pos):
"""
Return True if pos is inside the room.
pos: a Position object.
returns: True if pos is in the room, False otherwise.
"""
return (int(pos.getX()), int(pos.getY())) in self.room_coordinates
如您所见，我使用 int() 方法和随机生成器“random.randrange”实现了它。
在解决方案中，老师使用 math.floor() 函数和随机生成器 random.random() 实现了这个类:
class RectangularRoom(object):
"""
A RectangularRoom represents a rectangular region containing clean or dirty
tiles.
A room has a width and a height and contains (width * height) tiles. At any
particular time, each of these tiles is either clean or dirty.
"""
def __init__(self, width, height):
"""
Initializes a rectangular room with the specified width and height.
Initially, no tiles in the room have been cleaned.
width: an integer > 0
height: an integer > 0
"""
self.width = width
self.height = height
self.tiles = {}
for x in range(self.width):
for y in range(self.height):
self.tiles[(x, y)] = False
def cleanTileAtPosition(self, pos):
"""
Mark the tile under the position POS as cleaned.
Assumes that POS represents a valid position inside this room.
pos: a Position
"""
x = math.floor(pos.getX())
y = math.floor(pos.getY())
self.tiles[(x, y)] = True
def isTileCleaned(self, m, n):
"""
Return True if the tile (m, n) has been cleaned.
Assumes that (m, n) represents a valid tile inside the room.
m: an integer
n: an integer
returns: True if (m, n) is cleaned, False otherwise
"""
return self.tiles[(m, n)]
def getNumTiles(self):
"""
Return the total number of tiles in the room.
returns: an integer
"""
return self.width * self.height
def getNumCleanedTiles(self):
"""
Return the total number of clean tiles in the room.
returns: an integer
"""
return sum(self.tiles.values())
def getRandomPosition(self):
"""
Return a random position inside the room.
returns: a Position object.
"""
return Position(random.random() * self.width,
random.random() * self.height)
def isPositionInRoom(self, pos):
"""
Return True if pos is inside the room.
pos: a Position object.
returns: True if pos is in the room, False otherwise.
"""
return ((0 <= pos.getX() < self.width)
and (0 <= pos.getY() < self.height))
令人惊讶的是，这两段代码产生了完全不同的结果。我想知道为什么会这样。 int() 和 floor() 对正数应该有相同的效果，这两个随机函数似乎产生相似的数字。
请您参考如下方法:
嗯，我不知道你问题的答案 - 我怀疑他们返回的是完全相同的东西。但是，我认为您的解决方案存在问题，可能会解释输出:
在“cleanTileAtPosition”中
self.cleaned.append((int(pos.getX()), int(pos.getY())))
在“getNumCleanedTiles”中
return len(self.cleaned)
此代码似乎允许多次清洁瓷砖。这不是您的教师代码所做的，因为磁贴只能设置为“True”一次。
(顺便说一句，因为 random.randrange 返回一个整数.. 整数转换应该什么都不做!)
编辑:另外 - 我认为类型差异值得考虑。但是您所有的类型都是“整数”，所以这应该不是问题。
