python - 如何从字符串字符构建所有可能的对

Question

我想从一个字符串中构建包含字符串字符所有可能组合的对。

# Exemple :
s = "ABCD"

# Desired result :
["A", "BCD"]
["B", "ACD"]
["C", "ABD"]
...
["AB", "CD"]
...
["BC", "AD"]
...
["ABC", "D"]
["ABD", "C"]
["ACD", "B"]
["BCD", "A"]

Answer 1

一种方法是生成索引的组合，而不是随着r的增加生成元素本身:1, 2, .., length - 1。然后我们找到剩余的组合选择后的索引。 itemgetter 可以获取给定索引的值，我们可以将它们作为字符串收集在列表中:

from itertools import combinations
from operator import itemgetter

# given string and range till its length
s = "ABCD"
rng = range(len(s))

result = []
# for each combination possibility r...
for r in range(1, len(s)):
    # get the indices from `rng`
    for inds in combinations(rng, r):
        # find `others` that are not `inds` in `rng`
        others = [ind for ind in rng if ind not in inds]

        # now index into the string with these indices to find pairs
        first = itemgetter(*inds)(s)
        second = itemgetter(*others)(s)

        # store the stringifed pair
        result.append(["".join(first), "".join(second)])

给出

>>> result

[["A", "BCD"],
 ["B", "ACD"],
 ["C", "ABD"],
 ["D", "ABC"],
 ["AB", "CD"],
 ["AC", "BD"],
 ["AD", "BC"],
 ["BC", "AD"],
 ["BD", "AC"],
 ["CD", "AB"],
 ["ABC", "D"],
 ["ABD", "C"],
 ["ACD", "B"],
 ["BCD", "A"]]