計算字符串中整個單詞的出現次數

Question

我想找到字符串中特定單詞的出現次數。

我在網上搜索並找到了很多答案，例如

• 堆棧溢出答案
• 來自 DotNetPerl 的回答

但他們都沒有給我准確的結果。

我想要的是：

輸入：

I have asked the question in StackOverflow. Therefore i can expect answer here.

“The”關鍵字的輸出：

The keyword count: 2

注意：它不應該考慮句子中的“The”和“The”。

基本上我想匹配整個單詞並得到計數。

Answer 1

像這樣嘗試

var searchText=" the ";
var input="I have asked the question in StackOverflow. Therefore i can expect answer here.";
var arr=input.Split(new char[]{' ','.'});
var count=Array.FindAll(arr, s => s.Equals(searchText.Trim())).Length;
Console.WriteLine(count);

網吧

編輯

對於你的搜索句子

var sentence ="I have asked the question in StackOverflow. Therefore i can expect answer here.";
var searchText="have asked";
char [] split=new char[]{',',' ','.'};
var splitSentence=sentence.ToLower().Split(split);
var splitText=searchText.ToLower().Split(split);
Console.WriteLine("Search Sentence {0}",splitSentence.Length);
Console.WriteLine("Search Text {0}",splitText.Length);
var count=0;
for(var i=0;i<splitSentence.Length;i++){
    if(splitSentence[i]==splitText[0]){
      var index=i;
        var found=true;
        var j=0;
        for( j=0;j<splitText.Length;j++){
          if(splitSentence[index++]!=splitText[j])
          {
              found=false;
              break;
          }
        }
        if(found){
            Console.WriteLine("Index J {0} ",j);
            count++;
            i= index >i ? index-1 : i;
        }
    }

}
Console.WriteLine("Total found {0} substring",count);

網吧

Answer 2

一個可能的解決方案是使用正則表達式：

var count = Regex.Matches(input.ToLower(), String.Format("\b{0}\b", "the")).Count;

Answer 3

試試這樣（方式1）

string SpecificWord = " the ";
            string sentence = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
            int count = 0;
            foreach (Match match in Regex.Matches(sentence, SpecificWord, RegexOptions.IgnoreCase))
            {
                count++;
            }
            Console.WriteLine("{0}" + " Found " + "{1}" + " Times", SpecificWord, count);

或像這樣（方式2）

string SpecificWord = " the ";
string sentence = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
int WordPlace = sentence.IndexOf(SpecificWord);
Console.WriteLine(sentence);
int TimesRep;
for (TimesRep = 0; WordPlace > -1; TimesRep++)
{
    sentence = (sentence.Substring(0, WordPlace) +sentence.Substring(WordPlace +SpecificWord.Length)).Replace("  ", " ");
    WordPlace = sentence.IndexOf(SpecificWord);
}

Console.WriteLine("this word Found " + TimesRep + " time");

Answer 4

您可以使用 while 循環來搜索第一次出現的索引，然后從找到的索引 ++ 位置進行搜索，並在循環末尾設置一個計數器。 While 循環一直持續到 index == -1。

Answer 5

像這樣嘗試

string Text = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
                Text = Text.ToLower();
                Dictionary<string, int> frequencies = null;
                frequencies = new Dictionary<string, int>();
                string[] words = Regex.Split(Text, "\\W+");
                foreach (string word in words)
                {
                    if (frequencies.ContainsKey(word))
                    {
                        frequencies[word] += 1;
                    }
                    else
                    {
                        frequencies[word] = 1;
                    }
                }


                foreach (KeyValuePair<string, int> entry in frequencies)
                {
                    string word = entry.Key;
                    int frequency = entry.Value;
                    Response.Write(word.ToString() + "," + frequency.ToString()+"</br>");
                }

並搜索特定單詞然后嘗試像這樣。

string Text = "I have asked the question in StackOverflow. Therefore the i can expect answer here.";
        Text = Text.ToLower();
        string searchtext = "the";
        searchtext = searchtext.ToLower();
        string[] words = Regex.Split(Text, "\\W+");
        foreach (string word in words)
        {
            if (searchtext.Equals(word))
            {
                count = count + 1;
            }
            else
            {
            }
        }
        Response.Write(count);

Answer 6

嗯，問題並不像你想象的那么簡單； 有許多問題應該注意，例如標點符號、字母大小寫以及如何識別單詞邊界之類的問題。 但是使用N_Gram概念，我提供了以下解決方案：

1- 確定密鑰中有多少個單詞。 將其命名為 N

2- 提取文本中所有 N 個連續的單詞序列 (N_Grams)。

3- 計算 N_Grams 中 key 的出現次數

    string text = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
    string key = "the question";
    int gram = key.Split(' ').Count();
    var parts = text.Split(' ');
    List<string> n_grams = new List<string>();
    for (int i = 0; i < parts.Count(); i++)
    {
        if (i <= parts.Count() - gram)
        {
            string sequence = "";
            for (int j = 0; j < gram; j++)
            {
                sequence += parts[i + j] + " ";
            }
            if (sequence.Length > 0)
                sequence = sequence.Remove(sequenc.Count() - 1, 1);
            n_grams.Add(sequence);
        }
    }

    // The result
    int count = n_grams.Count(p => p == key);

}

例如對於 key = the question並考慮single space作為單詞邊界，提取以下二元組：

我有
問過了
問
問題
提問
在 StackOverflow 中。
堆棧溢出。 所以
因此我
我可以
可以期待
期待答案
在這里回答。

並且the question在文中出現的次數不明顯：1

Answer 7

此解決方案應該適用於字符串所在的任何地方：

var str = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
var numMatches = Regex.Matches(str.ToUpper(), "THE")
    .Cast<Match>()
    .Count(match => 
        (match.Index == 0 || str[match.Index - 1] == ' ') && 
        (match.Index + match.Length == str.Length || 
            !Regex.IsMatch(
                str[match.Index + match.Length].ToString(),
                "[a-zA-Z]")));

.NET 小提琴

Answer 8

string input = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
string pattern = @"\bthe\b";
var matches = Regex.Matches(input, pattern, RegexOptions.IgnoreCase);
Console.WriteLine(matches.Count);

請參閱正則表達式錨點- "\\b"。

Answer 9

Count 出現在字符串中的整個單詞的可能性有很多。
例如

第一的：

string name = "pappu kumar sdffnsd sdfnsdkfbsdf sdfjnsd fsdjkn fsdfsd sdfsd pappu kumar";
var res= name.Contains("pappu kumar");
var splitval = name.Split("pappu kumar").Length-1;

第二：

var r = Regex.Matches(name, "pappu kumar").Count;

Answer 10

怎么樣（似乎比其他解決方案更有效）：

public static int CountOccurences(string haystack, string needle)
{
    return (haystack.Length - haystack.Replace(needle, string.Empty).Length) / needle.Length;
}

Answer 11

試試這也適用於結構化數據。

    var splitStr = inputStr.Split(' ');
    int result_count = splitStr.Count(str => str.Contains("userName"));