python - 如何根据每个元组中第一个数字的值从元组列表中弹出项目？

Question

我正在尝试创建一个包含一组数字的所有变体的元组列表。但是，我想从列表中删除任何序列相同但偏移一两个位置的变体。例如： (-1,1,2), (1,2,-1)&(2,-1,1)我只想要第一个。

这就是我要做的事情：

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)

这导致：

[(-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)]

那么接下来我该怎么做才能过滤结果，所以我只有我想要的结果，它们是：

[(-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)]

如果它有助于列表之间的一个简单区别是我想要的列表是以-1开头的所有元组，以及没有以0开头的-1的元组

标签： pythonpython-3.x

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)]