多列表的所有可能组合

Question

list_a = [("A","<",1), ("A","==",5)]
list_b = [("B","<",5), ("B","==",7), ("B",">=",8)]
list_c = [("C","<",10),("C","<=",6),("C",">",4),("C","<=",6)]

我想列出所有可能的组合，每个列表只能有一个可接受的限制。

我可以看到 itertools.product 有点接近我想要的，而且我知道我可以做类似

的事情

new_list = []
for a in list_a:
  for b in list_b:
    for c in list_c
      new_list.append(list(itertools.combinations([a,b,c],2)))

但是这里的 n**3 复杂性似乎是一个非常糟糕的解决方案，因为我希望最终使用 9 个列表（即 list_c、list_d、list_e, 等...) 尺寸 30+ 以下是一些可接受的可能输出：

[("A","<",1)]
[("A","<",1),("B","<",5)]
[("A","<",1),("B","==",7)]
[("A","<",1),("B",">=",8)]
[("A","<",1),("B",">=",8),("C","<",10)]

基本上我理解当你有一组 select 数字时 itertools 的用法，例如 itertools.product(('ABCD'),3) 会给出 AAA 的输出， AAB、AAC、AAD、BAA、BAB、BAC 等，但我似乎无法弄清楚如何使用 stdlib 将 "only one per list" 约束应用到最大扩展而不破解一些非常低效的解决方案。

Answer 1

怎么样：

import itertools

list_a = [("A","<",1), ("A","==",5)]
list_b = [("B","<",5), ("B","==",7), ("B",">=",8)]
list_c = [("C","<",10),("C","<=",6),("C",">",4),("C","<=",6)]

lists = [list_a, list_b, list_c]


for l in lists: l.insert(0, None)

for x in itertools.product(*lists):
    print list(filter(None, x))

对于这些列表，我得到 60 个元素，包括一个空元素。

作为参考，下面列出了您的示例元素的索引：

[("A","<",1)]                           # 20
[("A","<",1),("B","<",5)]               # 25
[("A","<",1),("B","==",7)]              # 30
[("A","<",1),("B",">=",8)]              # 35
[("A","<",1),("B",">=",8),("C","<",10)] # 36

多列表的所有可能组合

Every possible combination of a multi-list

python

iterator

generator

itertools

python-3.x