F#将Array2转换为列表 [英] F# convert Array2 into a list

问题描述

我对函数式编程还是很陌生，所以如果我不知道该怎么做，我会恢复为程序样式.我找到了一种不必转换为列表的方法，但是我仍然想知道如何.

I'm still new to functional programming so if I can't figure out how to do something I revert back to procedural style. I found a way to get around having to convert to a list but I'd still like to know how.

这是我尝试将二维数组转换为列表的方法.

Here is my attempt to convert a two dimensional array to a list.

let board = Array2.init 10 20 (fun i j -> pull(i, j))

let mutable pieces = []

board
|> Array2.mapi (fun i j a -> transform(i, j, a))
|> Array2.iter (fun a -> (pieces <- a :: pieces))

推荐答案

显然，在.Net中，多维数组是IEnumerable(非通用)的，因此这行得通:

Apparently in .Net, multi-dimensional arrays are IEnumerable (non-generic), and thus this works:

let a2 = Array2.init 2 3 (fun x y -> (x+1)*(y+1))
let l = a2 |> Seq.cast<int> |> Seq.fold (fun l n -> n :: l) []
printfn "%A" l

正如Noldorin在评论中指出的那样，这甚至更好:

As Noldorin points out in a comment, this is even better:

let l = a2 |> Seq.cast<int> |> Seq.toList

这篇关于F#将Array2转换为列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！