sorting - 如何根据 haskell 中另一个向量的排序顺序对向量值进行重新排序？

Question

假设我有两个向量:

  let x = V.fromList ["foo", "bar", "baz"]
  let y = V.fromList [1,3,2]

我想定义一个向量 y'，它是 y 的排序版本，但我还想定义一个重新排序的 x'它是根据 y 的排序顺序排序的(x' 应该看起来像 ["foo", "baz", "bar"] ).

最好的功能是什么？理想情况下，我想避免从头开始编写排序函数。

Answer 1

我想你在找backpermute

backpermute :: Vector a -> Vector Int -> Vector a

O(n) Yield the vector obtained by replacing each element i of the index vector by xs!i. This is equivalent to map (xs!) is but is often much more efficient.