Question

我想查看列表是否包含在另一个列表中并从列表列表中提取该列表，例如我想查看["bc","abc"]中是否包含[["a","b","c","a","b","c","de"],["a","bc","abc","de"],["a","bc","abc","d","e"],....]并且我想制作列出特定列表的列表，例如[["a","bc","abc","de"],["a","bc","abc","d","e"]]。对于[["aabbcc","aacc"]]，我想仅匹配此["cc","aabbcc","aacc"]或["c","c","aabbcc","aacc"]但不匹配[["ccaabbcc","aacc"]]。有人能帮助我吗？

Answer 1

根据我的理解，你想要一些关心列表中元素顺序的东西

如果你关心元素的顺序：

import Data.List (subsequences)

included :: Eq a => [a] -> [[a]] -> [[a]]
included ls nest = filter (\x -> any (ls==) $ subsequences x) nest

TEST：

*Main> included [1,2,3,4] [[1,3,4,5,2],[1,2,4,5],[1,2,3,4,5]]
[[1,2,3,4,5]]

如果您不关心元素的顺序：

import Data.List (subsequences, permutations, concat)

included :: Eq a => [a] -> [[a]] -> [[a]]
included ls nest = filter func nest
  where
    func x = any (ls==) $ concat $ map subsequences $ permutations x

TEST：

*Main> included [1,2,3,4] [[1,3,4,5,2],[1,2,4,5],[1,2,3,4,5]]
[[1,3,4,5,2],[1,2,3,4,5]]

Answer 2

假设评论中我的问题的答案是否定的，

import Data.List

g :: (Eq a) => [a] -> [[a]] -> [[a]]
g a xs = [x | x <- xs, 
              or [and . map (uncurry (==)) $ zip a y | y <- init $ tails x]]

测试：

Prelude Data.List> g ["bc","abc"] [["a","bc","a","abc","de"],["a","bc","abc","de
"],["a","bc","abc","d","e"]]
[["a","bc","abc","de"],["a","bc","abc","d","e"]]

Answer 3

假设评论中Will的问题答案为“否”：

import Data.List (isInfixOf)

foo :: Eq a => [a] -> [[a]] -> [[a]]
foo needle haystack = filter (needle `isInfixOf`) haystack

（未测试）。

列表包含在haskell的另一个列表中

3 个答案: