从旧列表

Question

我有一个包含5个元素的列表，x + 2，x ^ 3 + x ^ 2 + x + 2，x ^ 3 + x ^ 2 + 2，x ^ 3 + 2x ^ 2 + 2x + 2，x ^ 3 + 2×2 +。我试图获得一个包含(x+2)(x^3+x^2+x+2), (x+2)(x^3+x^2+x+2)(x^3+x^2+2)等元素的大清单。一个元素乘以其他四个元素以获得新元素。我知道的唯一方法是使用For循环来做它，但它没有给我正确的列表。这就是我所拥有的：

L = ['x+2','x^3+x^2+x+2','x^3+x^2+2','x^3+2x^2+2x+2','x^3+2x+2']

for i in range(0,len(L)): 
    for j in range(1,len(L)):
        for k in range(2,len(L)):
            for l in range(3,len(L)):
                for m in range(4,len(L)):
                    print L[i],L[j],L[k],L[l],L[m]

我有很多重复元素，我想知道如何在生成列表时避免使用这些重复元素。谁能告诉我怎么做？

Answer 1

您可以使用combinations函数获取列表的所有组合：

from itertools import combinations
    result = []
    for i in range(1,len(L)):
        result.append(list(combinations(L,i))
    result # [[('x+2',), ('x^3+x^2+x+2',), ('x^3+x^2+2',), ('x^3+2x^2+2x+2',), ('x^3+2x+2',)], [('x+2', 'x^3+x^2+x+2'), ('x+2', 'x^3+x^2+2'), ('x+2', 'x^3+2x^2+2x+2'), ('x+2', 'x^3+2x+2'), ('x^3+x^2+x+2', 'x^3+x^2+2'), ('x^3+x^2+x+2', 'x^3+2x^2+2x+2'), ('x^3+x^2+x+2', 'x^3+2x+2'), ('x^3+x^2+2', 'x^3+2x^2+2x+2'), ('x^3+x^2+2', 'x^3+2x+2'), ('x^3+2x^2+2x+2', 'x^3+2x+2')], [('x+2', 'x^3+x^2+x+2', 'x^3+x^2+2'), ('x+2', 'x^3+x^2+x+2', 'x^3+2x^2+2x+2'), ('x+2', 'x^3+x^2+x+2', 'x^3+2x+2'), ('x+2', 'x^3+x^2+2', 'x^3+2x^2+2x+2'), ('x+2', 'x^3+x^2+2', 'x^3+2x+2'), ('x+2', 'x^3+2x^2+2x+2', 'x^3+2x+2'), ('x^3+x^2+x+2', 'x^3+x^2+2', 'x^3+2x^2+2x+2'), ('x^3+x^2+x+2', 'x^3+x^2+2', 'x^3+2x+2'), ('x^3+x^2+x+2', 'x^3+2x^2+2x+2', 'x^3+2x+2'), ('x^3+x^2+2', 'x^3+2x^2+2x+2', 'x^3+2x+2')], [('x+2', 'x^3+x^2+x+2', 'x^3+x^2+2', 'x^3+2x^2+2x+2'), ('x+2', 'x^3+x^2+x+2', 'x^3+x^2+2', 'x^3+2x+2'), ('x+2', 'x^3+x^2+x+2', 'x^3+2x^2+2x+2', 'x^3+2x+2'), ('x+2', 'x^3+x^2+2', 'x^3+2x^2+2x+2', 'x^3+2x+2'), ('x^3+x^2+x+2', 'x^3+x^2+2', 'x^3+2x^2+2x+2', 'x^3+2x+2')]]

Answer 2

您正在寻找的词是排列

Python在itertools包中有that ability included