我可以簡化此LINQ查詢

Question

我正在學習LINQ，我想知道是否可以簡化以下LINQ查詢...

現在我有兩個字符串，我解析連接的字符串來計算每個單詞的使用。 我想知道是否可以保留一個LINQ表達式，但不必復制from和let表達式中的string.Concat部分。

        string sentence = "this is the first sentence";
        string sentence2 = "this is the second sentence";

        var res = from word in string.Concat(sentence, sentence2).Split()
                  let combinedwords = string.Concat(sentence, sentence2).Split()
                  select new { TheWord = word, Occurance = combinedwords.Count(x => x.Equals(word)) };

Answer 1

您的查詢返回一個有點奇怪的結果集：

TheWord         Occurrence
this            1
is              2
the             2
first           1
sentencethis    1
is              2
the             2
second          1
sentence        1

這是你想要的，或者你更喜歡結果更像這樣？

TheWord         Occurrence
this            2
is              2
the             2
first           1
sentence        2
second          1

要獲得這些結果，您可以執行以下操作：

var res = from word in sentence.Split()
                               .Concat(sentence2.Split())
          group word by word into g
          select new { TheWord = g.Key, Occurrence = g.Count() };

另外一個選項; 更好（理論）性能但不太可讀：

var res = sentence.Split()
                  .Concat(sentence2.Split())
                  .Aggregate(new Dictionary<string, int>(),
                             (a, x) => {
                                           int count;
                                           a.TryGetValue(x, out count);
                                           a[x] = count + 1;
                                           return a;
                                       },
                             a => a.Select(x => new {
                                                        TheWord = x.Key,
                                                        Occurrence = x.Value
                                                    }));