转换一个IOrderedEnumerable< KeyValuePair<字符串，整数>>成字典<字符串，整数> [英] Convert an IOrderedEnumerable<KeyValuePair<string, int>> into a Dictionary<string, int>

问题描述

我是继回答另一个问题，和我：

  // itemCounter是一个字典<字符串，整数>和我只是想保持
 //键/与顶级maxAllowed值对值
如果（itemCounter.Count> maxAllowed）{
 IEnumerable的< KeyValuePair<字符串，整数>> sortedDict = $ B从itemCounter排序依据entry.Value降选择中入口$ B; 
 sortedDict = sortedDict.Take（maxAllowed）; 
 itemCounter = sortedDict.ToDictionary<字符串，整数>（/ *我该怎么办这里* /？）; 
} 
  

Visual Studio的要求参数 Func键<字符串， INT>的KeySelectors 。我尝试以下几个半相关的例子，我在网上找到，放在 K => k.Key ，但给出了一个编译器错误：

'System.Collections中.Generic.IEnumerable< System.Collections.Generic.KeyValuePair<字符串，整数>>
不包含定义'ToDictionary和最好的
扩展方法重载
'System.Linq.Enumerable.ToDictionary< TSource，TKEY的>（System.Collections.Generic.IEnumerable< TSource>中
System.Func< TSource，TKEY的>）有一些无效参数

解决方案

您指定不正确的通用参数。你是说TSource是字符串，而实际上它是一个KeyValuePair

这是正确的：

  sortedDict.ToDictionary< KeyValuePair<字符串，整数>中字符串，整数>（对= GT; pair.Key，对= GT; pair.Value）; 
  

与短版之中：

  sortedDict.ToDictionary（双= GT; pair.Key，对= GT; pair.Value）; 
  

I was following the answer to another question, and I got:

// itemCounter is a Dictionary<string, int>, and I only want to keep
// key/value pairs with the top maxAllowed values
if (itemCounter.Count > maxAllowed) {
    IEnumerable<KeyValuePair<string, int>> sortedDict =
        from entry in itemCounter orderby entry.Value descending select entry;
    sortedDict = sortedDict.Take(maxAllowed);
    itemCounter = sortedDict.ToDictionary<string, int>(/* what do I do here? */);
}

Visual Studio's asking for a parameter Func<string, int> keySelector. I tried following a few semi-relevant examples I've found online and put in k => k.Key, but that gives a compiler error:

'System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string,int>>' does not contain a definition for 'ToDictionary' and the best extension method overload 'System.Linq.Enumerable.ToDictionary<TSource,TKey>(System.Collections.Generic.IEnumerable<TSource>, System.Func<TSource,TKey>)' has some invalid arguments

解决方案

You are specifying incorrect generic arguments. You are saying that TSource is string, when in reality it is a KeyValuePair.

This one is correct:

sortedDict.ToDictionary<KeyValuePair<string, int>, string, int>(pair => pair.Key, pair => pair.Value);

with short version being:

sortedDict.ToDictionary(pair => pair.Key, pair => pair.Value);

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