c# - Minimize LINQ string token counter

Question

Followup on answer to an earlier question.

Is there a way to further reduce this, avoiding the external String.Split call? The goal is an associative container of {token, count}.

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

As you have it right now, it will work (to some extent) but is terribly inefficient. As is, the result is an enumeration of groupings, not the (word, count) pairs you might be thinking.

That overload of GroupBy() takes a function to select the key. You are effectively performing that calculation for every item in the collection. Without going the route of using regular expressions ignoring punctuation, it should be written like so:

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);