Python - 如何从嵌套列表中获取所有可能的组合

Question

I have a nested list like this :

values = [['DNO', 0.2], ['Equinor', 0.4], ['Petoro', 0.2], ['Total', 0.2]]

How to get all possible combinations of elements that will have a sum(2nd element of each sub list) greater than 0.5?

This is what I am using :

def getCombinations(values, min_len):
    combo = "\n"
    numbers = []
    doc = {}
    for val in values:
        doc[val[0]] = val[1]
        numbers.append(val[1])

    result = [seq for i in range(len(numbers), 0, -1) for seq in itertools.combinations(numbers, i) if sum(seq) >= 0.5]
    temp = doc.copy()

    for r in result:
        doc = temp.copy()
        if len(r) >= min_len:
            for rr in r:
                combo = combo + get_key(doc, rr) + " "

                doc.pop(get_key(doc, rr))
            combo = combo + "\n"
    return combo

My algorithm have some problem when there are multiple values like 0.2 in above list.

Currently it is returning this with min_length=3 :

Total Equinor Petoro DNO
Total Equinor Petoro 
Total Equinor Petoro 
Total Petoro DNO 
Equinor Total Petoro 

Answer 1

The following should work:

import itertools  
result=[] 
for k in range(2,len(values)+1):
    temp=[tuple(x[0] for x in i) for i in list(itertools.combinations(values,k))if sum([p[1] for p in i]) >0.5]
    result.append(temp)
result=sum(result, [])
print(result)

Output:

[('DNO', 'Equinor'), ('Equinor', 'Petoro'), ('Equinor', 'Total'), ('DNO', 'Equinor', 'Petoro'), ('DNO', 'Equinor', 'Total'), ('DNO', 'Petoro', 'Total'), ('Equinor', 'Petoro', 'Total'), ('DNO', 'Equinor', 'Petoro', 'Total')]

Answer 2

You can use a list comprehension like this:

Explanation:

• The first for defines the length of the combinations. Every length from 2 to the length of values is used.
• The second for creates the actual combinations
• The if uses a generator method to sum the numbers of the items

from itertools import combinations

combis = [
    item
    for length in range(2, len(values)+1)
    for item in combinations(values, length)
    if sum(i[1] for i in item) >= 0.5
]