c# - 最小化 LINQ 字符串 token 计数器

Question

跟进对 an earlier question 的回答.

有没有办法进一步减少这种情况，避免外部 String.Split 调用？目标是 {token, count} 的关联容器。

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

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

Answer 1

正如您现在拥有的那样，它会(在某种程度上)起作用，但效率极低。实际上，结果是分组的枚举，而不是您可能会想到的(单词，计数)对。

GroupBy() 的重载需要一个函数来选择键。您正在为集合中的每个项目有效地执行该计算。如果不使用忽略标点符号的正则表达式，应该这样写:

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";

var results = src.Split()               // default split by whitespace
                 .GroupBy(str => str)   // group words by the value
                 .Select(g => new
                              {
                                  str = g.Key,      // the value
                                  count = g.Count() // the count of that value
                              });

// sort the results by the words that were counted
var sortedResults = results.OrderByDescending(p => p.str);