Question

如何将词典“转换”为序列，以便按键值排序？

let results = new Dictionary()

results.Add("George", 10)
results.Add("Peter", 5)
results.Add("Jimmy", 9)
results.Add("John", 2)

let ranking = 
  results
  ???????
  |> Seq.Sort ??????
  |> Seq.iter (fun x -> (... some function ...))

Answer 1

System.Collections.Dictionary＆lt; K，V＆gt;是IEnumerable＆lt; KeyValuePair＆lt; K，V＆gt;＆gt;，F＃Active Pattern'KeyValue'对于分解KeyValuePair对象很有用，所以：

open System.Collections.Generic
let results = new Dictionary<string,int>()

results.Add("George", 10)
results.Add("Peter", 5)
results.Add("Jimmy", 9)
results.Add("John", 2)

results
|> Seq.sortBy (fun (KeyValue(k,v)) -> k)
|> Seq.iter (fun (KeyValue(k,v)) -> printfn "%s: %d" k v)

Answer 2

您可能还会发现dict功能很有用。让F＃为你做一些类型推断：

let results = dict ["George", 10; "Peter", 5; "Jimmy", 9; "John", 2]

> val results : System.Collections.Generic.IDictionary<string,int>

Answer 3

另一个选项，在结束之前不需要lambda

{{1}}

在https://gist.github.com/theburningmonk/3363893

的帮助下

如何将字典“转换”为F＃中的序列？

3 个答案: