Python 对象列表，获取属性的所有“方向”

Question

我有一个对象列表（矩形）。每个对象有 2 个属性（高度和宽度）。我想得到这个列表的所有“方向”（不知道如何准确地调用它），所以所有 2^n（对于 n 个矩形的列表）方向，其中矩形的高度和宽度（可能）交换.对于 3 个对象的列表，它看起来像这样（顺序并不重要）：

[R1(w, h), R2(w2, h2), R3(w3, h3)]
[R1(w, h), R2(w2, h2), R3(h3, w3)]
[R1(w, h), R2(h2, w2), R3(w3, h3)]
[R1(w, h), R2(h2, w2), R3(h3, w3)]
[R1(h, w), R2(w2, h2), R3(w3, h3)]
[R1(h, w), R2(w2, h2), R3(h3, w3)]
[R1(h, w), R2(h2, w2), R3(w3, h3)]
[R1(h, w), R2(h2, w2), R3(h3, w3)]

我的矩形类如下所示：

class Rectangle:
    def __init__(self, height, width):
        self.height = height
        self.width = width

    def place(self):
        """Method to place tile in a larger grid"""

    def remove(self):
        """Method to remove tile from larger grid"""

有没有简单的方法可以做到这一点？

Answer 1

准备工作：

class Rectangle:
    def __init__(self, height, width):
        self.height = height
        self.width = width

    def flipped(self):
        return Rectangle(self.width, self.height)

    def __repr__(self):
        return 'Rectangle({}, {})'.format(self.height, self.width)

rectangles = [Rectangle(1, 10), Rectangle(2, 20), Rectangle(3, 30)]

解决方案：

from itertools import product
for orientation in product(*zip(rectangles, map(Rectangle.flipped, rectangles))):
    print(orientation)

输出：

(Rectangle(1, 10), Rectangle(2, 20), Rectangle(3, 30))
(Rectangle(1, 10), Rectangle(2, 20), Rectangle(30, 3))
(Rectangle(1, 10), Rectangle(20, 2), Rectangle(3, 30))
(Rectangle(1, 10), Rectangle(20, 2), Rectangle(30, 3))
(Rectangle(10, 1), Rectangle(2, 20), Rectangle(3, 30))
(Rectangle(10, 1), Rectangle(2, 20), Rectangle(30, 3))
(Rectangle(10, 1), Rectangle(20, 2), Rectangle(3, 30))
(Rectangle(10, 1), Rectangle(20, 2), Rectangle(30, 3))

Answer 2

这里有一些 Python 代码可以满足您的需求。如果您修复了show() 函数中的打印语句，它应该很容易在 Python 3 上运行。

#!/usr/bin/env python

''' Build a list of lists containing all combinations of orientations
    (i.e. landscape & portrait) for a list of Rectangle objects

    From http://stackoverflow.com/q/29988288/4014959

    Written by PM 2Ring 2015.05.02
'''

from itertools import product

#A simple rectangle class
class Rectangle(object):
    def __init__(self, width, height):
        self.width = width
        self.height = height

    def __repr__(self):
        return 'Rectangle({0}, {1})'.format(self.width, self.height)

    def transpose(self):
        return Rectangle(self.height, self.width)

#Helper function to print sequences
def show(seq):
    for item in seq:
        print item
    print

#A list of rectangle objects
rects_orig = [
    Rectangle(1, 2), 
    Rectangle(3, 4), 
    Rectangle(5, 6),
]
show(rects_orig)

#The transposed versions of those rectangles
rects_rot = [rect.transpose() for rect in rects_orig]
show(rects_rot)

#Join both lists into a list of tuples
rects_both = zip(rects_orig, rects_rot) 
show(rects_both)

#Build the combinations.
combos = [] 
for align in product([0, 1], repeat=len(rects_both)):
   combos.append([rect_pair[a] for a, rect_pair in zip(align, rects_both)])

show(combos)

输出

Rectangle(1, 2)
Rectangle(3, 4)
Rectangle(5, 6)

Rectangle(2, 1)
Rectangle(4, 3)
Rectangle(6, 5)

(Rectangle(1, 2), Rectangle(2, 1))
(Rectangle(3, 4), Rectangle(4, 3))
(Rectangle(5, 6), Rectangle(6, 5))

[Rectangle(1, 2), Rectangle(3, 4), Rectangle(5, 6)]
[Rectangle(1, 2), Rectangle(3, 4), Rectangle(6, 5)]
[Rectangle(1, 2), Rectangle(4, 3), Rectangle(5, 6)]
[Rectangle(1, 2), Rectangle(4, 3), Rectangle(6, 5)]
[Rectangle(2, 1), Rectangle(3, 4), Rectangle(5, 6)]
[Rectangle(2, 1), Rectangle(3, 4), Rectangle(6, 5)]
[Rectangle(2, 1), Rectangle(4, 3), Rectangle(5, 6)]
[Rectangle(2, 1), Rectangle(4, 3), Rectangle(6, 5)]