用于序列的 F# array_chunk [英] F# array_chunk for Sequence

问题描述

我在制作序列时遇到了一些麻烦.基本上我需要将一个序列切割成一个数组序列.Seq.windowed 几乎做到了，但我不想要重复的元素.

I'm having some trouble making a sequence. Basically I need to chop a sequence into a sequence of arrays. Seq.windowed almost does it but I don't want duplicate elements.

我可以通过先将所有内容读入数组来得到我想要的东西，但我更愿意使用序列.

I can get what I want by reading everything into an array first but I'd rather use a sequence.

let array_chunk s (a:int[]) =
    Array.init (a.Length / s) (fun i -> Array.sub a (i * s) s)

someSequence |> Seq.to_array |> array_chunk 5

推荐答案

这是一个很好的命令式程序，可以与 seq 一起使用并生成任意大小的数组.如果序列不是 n，最后一个会更小.

Here's a nice imperative one that'll work with seq and generate arrays of any size. The last one will be smaller if the sequence isn't even by n.

let chunk n xs = seq {
    let i = ref 0
    let arr = ref <| Array.create n (Unchecked.defaultof<'a>)
    for x in xs do
        if !i = n then 
            yield !arr
            arr := Array.create n (Unchecked.defaultof<'a>)
            i := 0 
        (!arr).[!i] <- x
        i := !i + 1
    if !i <> 0 then
        yield (!arr).[0..!i-1] }

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