Question

我正在尝试创建一个由一组数字的所有变体组成的元组列表。但是，我想从列表中删除所有序列相同但由一个或两个位置偏移的变体。例如： (-1,1,2)，(1,2,-1)和(2,-1,1)我只想要第一个。

这是我要去的地方

import itertools as it

list = [-1, 0, 1, 2]
cycles = []

list_cycle_3 = it.permutations(cycles, 3)
list_cycle_4 = it.permutations(cycles, 4)

for item in list_cycle_3:
    cycles.append(item)

for item in list_cycle_4:
    cycles.append(item)

print(cycles)

结果是：

[(-1, 0, 1), (-1, 0, 2), (-1, 1, 0), (-1, 1, 2), (-1, 2, 0), (-1, 2, 1), 
(0, -1, 1), (0, -1, 2), (0, 1, -1), (0, 1, 2), (0, 2, -1), (0, 2, 1), 
(1, -1, 0), (1, -1, 2), (1, 0, -1), (1, 0, 2), (1, 2, -1), (1, 2, 0), 
(2, -1, 0), (2, -1, 1), (2, 0, -1), (2, 0, 1), (2, 1, -1), (2, 1, 0), 
(-1, 0, 1, 2), (-1, 0, 2, 1), (-1, 1, 0, 2), (-1, 1, 2, 0), (-1, 2, 0, 1), (-1, 2, 1, 0), (0, -1, 1, 2), (0, -1, 2, 1), (0, 1, -1, 2), (0, 1, 2, -1), 
(0, 2, -1, 1), (0, 2, 1, -1), (1, -1, 0, 2), (1, -1, 2, 0), (1, 0, -1, 2), 
(1, 0, 2, -1), (1, 2, -1, 0), (1, 2, 0, -1), (2, -1, 0, 1), (2, -1, 1, 0), 
(2, 0, -1, 1), (2, 0, 1, -1), (2, 1, -1, 0), (2, 1, 0, -1)]

接下来我该怎么做才能过滤结果，所以只有我想要的结果，

[(-1, 0, 1), (-1, 0, 2), (-1, 1, 0), (-1, 1, 2), (-1, 2, 0), (-1, 2, 1), 
(0, 1, 2), (0, 2, 1), (-1, 0, 1, 2), (-1, 0, 2, 1), (-1, 1, 0, 2), 
(-1, 1, 2, 0), (-1, 2, 0, 1), (-1, 2, 1, 0)]

如果这有助于简化列表之间的区别，那就是我想要的列表是所有以-1开头的元组以及没有-1的以0开头的元组

Answer 1

    l=[(-1, 0, 1), (-1, 0, 2), (-1, 1, 0), (-1, 1, 2), (-1, 2, 0), (-1, 2, 1),                                                                                           
    (0, -1, 1), (0, -1, 2), (0, 1, -1), (0, 1, 2), (0, 2, -1), (0, 2, 1),
    (1, -1, 0), (1, -1, 2), (1, 0, -1), (1, 0, 2), (1, 2, -1), (1, 2, 0),
    (2, -1, 0), (2, -1, 1), (2, 0, -1), (2, 0, 1), (2, 1, -1), (2, 1, 0),
    (-1, 0, 1, 2), (-1, 0, 2, 1), (-1, 1, 0, 2), (-1, 1, 2, 0), (-1, 2, 0, 1), (-1, 2, 1, 0), (0, -1, 1, 2), (0, -1, 2, 1), (0, 1, -1, 2), (0, 1, 2, -1),
    (0, 2, -1, 1), (0, 2, 1, -1), (1, -1, 0, 2), (1, -1, 2, 0), (1, 0, -1, 2),
    (1, 0, 2, -1), (1, 2, -1, 0), (1, 2, 0, -1), (2, -1, 0, 1), (2, -1, 1, 0),
    (2, 0, -1, 1), (2, 0, 1, -1), (2, 1, -1, 0), (2, 1, 0, -1)]

   l2=[]

   for i in l:
       if i[0] == -1 :
           l2.append(i)

   print(l2)

此代码有效

输出

[(-1, 0, 1), (-1, 0, 2), (-1, 1, 0), (-1, 1, 2), (-1, 2, 0), (-1, 2, 1), (-1, 0, 1, 2), (-1, 0, 2, 1), (-1, 1, 0, 2), (-1, 1, 2, 0), (-1, 2, 0, 1), (-1, 2, 1, 0)]

Answer 2

从一个不包含您要过滤的数字的列表开始：

例如，您只需要以0开头的那个。那么您的列表就是

l = [-1, 1, 2]

查找所有两个元素排列并根据需要过滤它们。然后，Ant通过映射结果集将0作为第一个元素添加。

示例：

In [2]: from itertools import permutations
In [3]: l = [-1, 1, 2]
In [4]: p = permutations(l, 2)
In [5]: [(0, *t) for t in p]
Out[5]: [(0, -1, 1), (0, -1, 2), (0, 1, -1), (0, 1, 2), (0, 2, -1), (0, 2, 1)]

您可以对其中没有-1并从0开始（从列表中省略-1和0）的那些对象执行类似的操作，然后将0作为第一个元素添加到结果集项中。

也不要在代码中覆盖保留的关键字：

list =  [...] # do not do that

如何根据每个元组中第一个数字的值从一个元组列表中弹出项目？

2 个答案: