如何“转换”一个字典到F＃中的序列？ [英] How to "convert" a Dictionary into a sequence in F#?

问题描述

如何将Dictionary转换成序列，以便按键值进行排序？

How do I "convert" a Dictionary into a sequence so that I can sort by key value?

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 ...))

推荐答案

一个System.Collections.Dictionary< K，V>是一个IEnumerable< KeyValuePair< K，V >>，并且F＃活动模式'KeyValue'用于分解KeyValuePair对象，所以： p>

A System.Collections.Dictionary<K,V> is an IEnumerable<KeyValuePair<K,V>>, and the F# Active Pattern 'KeyValue' is useful for breaking up KeyValuePair objects, so:

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)

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