我想找到一个字符串中特定单词的出现次数。
我在网上搜索了很多类似的答案
但他们都没有给我准确的结果。
我想要的是：
输入：
I have asked the question in StackOverflow. Therefore i can expect answer here.
“The”关键字的输出：
The keyword count: 2
注意：不要在句子中考虑“Theore”中的“The”。
基本上我想匹配整个单词并获得计数。
【问题讨论】：
像这样尝试（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);
或像这样（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");
【讨论】：
试试这个也适用于结构化数据。
var splitStr = inputStr.Split(' ');
int result_count = splitStr.Count(str => str.Contains("userName"));
【讨论】：
怎么样（似乎比其他解决方案更有效）：
public static int CountOccurences(string haystack, string needle)
{
return (haystack.Length - haystack.Replace(needle, string.Empty).Length) / needle.Length;
}
【讨论】：
Count 在一个字符串中出现整个单词的可能性有很多。
例如
第一：
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;
【讨论】：
这样试试
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>");
}
要搜索特定的单词，然后尝试这样。
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);
【讨论】：
这样试试
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);
编辑
为您的搜索句子
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);
【讨论】：
The 应该有输出 1，I can 也应该有输出 1
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);
见正则表达式Anchors - "\b"。
【讨论】：
这个解决方案应该适用于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]")));
【讨论】：
问题并不像你想象的那么简单；应该注意许多问题，例如标点符号、字母大小写以及如何识别单词边界等问题。 但是使用N_Gram 概念我提供了以下解决方案：
1- 确定键中有多少个单词。将其命名为 N
2-提取文本中所有N个连续的单词序列（N_Grams）。
3- 统计 N_Grams 中 key 的出现次数
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);
}
例如对于键 = the question 并将 single space 视为单词边界，提取以下二元组：
我有
问过
问
问题
问题在
在 StackOverflow 中。
堆栈溢出。因此
所以我
我可以
可以期待
期待答案
在这里回答。
而the question在文中出现的次数不明显可见：1
【讨论】：
您可以使用 while 循环搜索第一次出现的索引，然后从找到的索引 ++ 位置进行搜索，并在循环结束时设置一个计数器。 While 循环一直持续到 index == -1。
【讨论】：
一个可能的解决方案是使用正则表达式：
var count = Regex.Matches(input.ToLower(), String.Format("\b{0}\b", "the")).Count;
【讨论】：