使用Walker的别名方法的加权随机选择(Weighted random selection using Walker's Alias Method)

我正在寻找这个算法 （从每个元素具有不同拾取概率（重量）的元素列表中随机选择的算法） 并发现只有python和c实现，我做了一个C＃之后，有点不同（但我认为更简单）我想我应该分享它，也需要一个F＃imlementation ，如果任何人都可以做出来，请发表一个答案

using System; using System.Collections.Generic; using System.Linq; namespace ChuckNorris { class Program { static void Main(string[] args) { var oo = new Dictionary<string, int> { {"A",7}, {"B",1}, {"C",9}, {"D",8}, {"E",11}, }; var rnd = new Random(); var pick = rnd.Next(oo.Values.Sum()); var sum = 0; var res = ""; foreach (var o in oo) { sum += o.Value; if(sum >= pick) { res = o.Key; break; } } Console.WriteLine("result is "+ res); } } }

如果任何人都可以在F＃中重制它，请发布您的代码

I was looking for this algorithm (algorithm which will randomly select from a list of elements where each element has different probability of being picked (weight) ) and found only python and c implementations, after I did a C# one, a bit different (but I think simpler) I thought I should share it, also I need an F# imlementation, if anyone can make it please post an answer

if anyone can remake it in F# please post your code

最满意答案

这里是F＃中的类似代码：

let rng = new System.Random()
let d = [| "A", 3
           "B", 2
           "C", 3 |]
let sums = Seq.scan (+) 0 (dict d).Values |> Seq.skip 1 |> Seq.toArray 
let pick = rng.Next(sums.[sums.Length-1])
let res = fst d.[sums |> Seq.findIndex ((<) pick)]
Here is the similar code in F#: 
let rng = new System.Random()
let d = [| "A", 3
           "B", 2
           "C", 3 |]
let sums = Seq.scan (+) 0 (dict d).Values |> Seq.skip 1 |> Seq.toArray 
let pick = rng.Next(sums.[sums.Length-1])
let res = fst d.[sums |> Seq.findIndex ((<) pick)]

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