How to find all elements in listB that contain some element in listA where listA and listB stores co-CodePudding

Suppose listA=[[0,1],[1,2]], which stores two 2-combinations from {0,1,2,3}. listB=[[0,1,2],[0,1,3],[0,2,3],[1,2,3]], which stores all possible 3-combinations from {0,1,2,3}.

How to find all elements in listB that include/contain at least one of the 2-combinations from listA?

My desired output is listC=[[0,1,2],[0,1,3],[1,2,3]], where [0,1,2] includes both [0,1] and [1,2], [0,1,3] includes [0,1], [1,2,3] includes [1,2].

Thanks!(It would be great if the answer codes is efficient and fast, as I need to do this for listA and listB that are of large scale)

I tried the following codes:

import numpy as np
import itertools
listA=[[0,1],[1,2]]
listB=[]
listCdup=[]
rows=range(4)
for combo in itertools.combinations(rows, 3):
    listB.append(list(combo))
print(listB)
for b in listB:
    for a in listA:
        if a.issubset(b):
            listCdup.append(b)
listC=np.unique(listCdup)

But there is an error that says list object has no attribute 'issubset'

CodePudding user response：

Hope this code can be a solution for your scenario, let me know if you think it needs any explanations:

listA=[[0,1],[1,2]]
listB=[[0,1,2],[0,1,3],[0,2,3],[1,2,3]]
res = []

for comA in listA:

    strA = " ".join(str(e) for e in comA)

    for comB in listB:
    
        strB = " ".join(str(el) for el in comB)
    
        if strA in strB:
        
            res.append(list(comB))


print(res)

CodePudding user response：

Here is a solution using itertools.combinations, comprehensions, and set:

>>> from itertools import combinations
>>> a = [(0, 1), (1, 2)]
>>> a
[(0, 1), (1, 2)]
>>> b = list(combinations(range(4), 3))
>>> b
[(0, 1, 2), (0, 1, 3), (0, 2, 3), (1, 2, 3)]
>>> c = set(bi for ai in a for bi in b if ai in set(combinations(bi, len(ai))))
>>> c
{(0, 1, 2), (0, 1, 3), (1, 2, 3)}
>>>

The solution above assumes that len(ai) <= len(bi) where ai and bi are elements of a and b, respectively. What it does is simply check if each element of a is an element of the combinations of each element of b combined by the len() of elements of a.