关键字.NET

Question

我需要计算每个关键字多少次重复发生在一个字符串，通过次数最多的排序。 用于此目的的.NET代码中可用的最快算法是什么？

Answer 1

编辑：下面的代码组，计

string[] target = src.Split(new char[] { ' ' }); 

var results = target.GroupBy(t => new 
{ 
    str = t, 
    count = target.Count(sub => sub.Equals(t)) 
}); 

这终于开始让我更有意义的独特记号......

编辑：下面的子目标相关的计数结果代码：

string src = "for each character in the string, take the rest of the " + 
    "string starting from that character " + 
    "as a substring; count it if it starts with the target string"; 
string[] target = {"string", "the", "in"}; 

var results = target.Select((t, index) => new {str = t, 
    count = src.Select((c, i) => src.Substring(i)). 
    Count(sub => sub.StartsWith(t))}); 

结果现在是：

+  [0] { str = "string", count = 4 } <Anonymous Type> 
+  [1] { str = "the", count = 4 } <Anonymous Type> 
+  [2] { str = "in", count = 6 } <Anonymous Type> 

下面

原始代码：

string src = "for each character in the string, take the rest of the " + 
    "string starting from that character " + 
    "as a substring; count it if it starts with the target string"; 
string[] target = {"string", "the", "in"}; 

var results = target.Select(t => src.Select((c, i) => src.Substring(i)). 
    Count(sub => sub.StartsWith(t))).OrderByDescending(t => t); 

与感激确认给this previous response。从调试

结果（这需要额外的逻辑包括匹配的字符串，其计数）：

-  results {System.Linq.OrderedEnumerable<int,int>}  
-  Results View Expanding the Results View will enumerate the IEnumerable 
     [0] 6 int 
     [1] 4 int 
     [2] 4 int 

Answer 2

您可以将字符串分解为一个字符串集合，每个字符一个字符串，然后对该集合执行LINQ查询。虽然我怀疑它会是最快的，但它可能比正则表达式更快。

Answer 3

说不上大约最快的，但LINQ的可能是最理解：

var myListOfKeywords = new [] {"struct", "public", ...}; 

var keywordCount = from keyword in myProgramText.Split(new []{" ","(", ...}) 
    group by keyword into g 
    where myListOfKeywords.Contains(g.Key) 
    select new {g.Key, g.Count()} 

foreach(var element in keywordCount) 
    Console.WriteLine(String.Format("Keyword: {0}, Count: {1}", element.Key, element.Count)); 

您可以在非LINQ的-Y方式写这篇文章，但基本前提是相同的;将字符串分成单词，并计算每个感兴趣单词的出现次数。

Answer 4

简单算法：将字符串拆分为单词数组，迭代该数组，并将每个单词的计数存储在散列表中。完成后按计数排序。