关键词提取1-C#

C# 中文分词算法(实现从文章中提取关键字算法)

using System;
using System.IO;
using System.Text;
using System.Collections;
using System.Collections.Generic;
using System.Text.RegularExpressions;
namespace LumkitCms.Utils
{
/// <summary>
/// 分词类
/// </summary>
public static class WordSpliter
{
#region 属性
private static string SplitChar = " ";//分隔符
#endregion
//
#region 数据缓存函数
/// <summary>
/// 数据缓存函数
/// </summary>
/// <param name="key">索引键</param>
/// <param name="val">缓存的数据</param>
private static void SetCache(string key, object val)
{
if (val == null)
val = " ";
System.Web.HttpContext.Current.Application.Lock();
System.Web.HttpContext.Current.Application.Set(key, val);
System.Web.HttpContext.Current.Application.UnLock();
}
/// <summary>
/// 读取缓存
/// </summary>
/// <param name="mykey"></param>
/// <returns></returns>
private static object GetCache(string key)
{
return System.Web.HttpContext.Current.Application.Get(key);
}
#endregion
//
#region 读取文本
private static SortedList ReadTxtFile(string FilePath)
{
if (GetCache("cms_dict") == null)
{
Encoding encoding = Encoding.GetEncoding("utf-8");
SortedList arrText = new SortedList();
//
try
{
FilePath = System.Web.HttpContext.Current.Server.MapPath(FilePath);
if (!File.Exists(FilePath))
{
arrText.Add("0", "文件" + FilePath + "不存在...");
}
else
{
StreamReader objReader = new StreamReader(FilePath, encoding);
string sLine = "";
//ArrayList arrText = new ArrayList();

while (sLine != null)
{
sLine = objReader.ReadLine();
if (sLine != null)
arrText.Add(sLine, sLine);
}
//
objReader.Close();
objReader.Dispose();
}
}
catch (Exception ex)
{
throw ex;
}
SetCache("cms_dict", arrText);
}
return (SortedList)GetCache("cms_dict");
}
#endregion
//
#region 载入词典
private static SortedList LoadDict(string dictfile)
{
return ReadTxtFile(dictfile);
}
#endregion
//
#region 判断某字符串是否在指定字符数组中
private static bool StrIsInArray(string[] StrArray, string val)
{
for (int i = 0; i < StrArray.Length; i++)
if (StrArray[i] == val) return true;
return false;
}
#endregion
//
#region 正则检测
private static bool IsMatch(string str, string reg)
{
return new Regex(reg).IsMatch(str);
}
#endregion
//
#region 首先格式化字符串(粗分)
private static string FormatStr(string val)
{
string result = "";
if (val == null || val == "")
return "";
//
char[] CharList = val.ToCharArray();
//
string Spc = SplitChar;//分隔符
int StrLen = CharList.Length;
int CharType = 0; //0-空白 1-英文 2-中文 3-符号
//
for (int i = 0; i < StrLen; i++)
{
string StrList = CharList[i].ToString();
if (StrList == null || StrList == "")
continue;
//
if (CharList[i] < 0x81)
{
#region
if (CharList[i] < 33)
{
if (CharType != 0 && StrList != "/n" && StrList != "/r")
{
result += " ";
CharType = 0;
}
continue;
}
else if (IsMatch(StrList, "[^0-9a-zA-Z@//.%#:///&_-]"))//排除这些字符
{
if (CharType == 0)
result += StrList;
else
result += Spc + StrList;
CharType = 3;
}
else
{
if (CharType == 2 || CharType == 3)
{
result += Spc + StrList;
CharType = 1;
}
else
{
if (IsMatch(StrList, "[@%#:]"))
{
result += StrList;
CharType = 3;
}
else
{
result += StrList;
CharType = 1;
}//end if No.4
}//end if No.3
}//end if No.2
#endregion
}//if No.1
else
{
//如果上一个字符为非中文和非空格，则加一个空格
if (CharType != 0 && CharType != 2)
result += Spc;
//如果是中文标点符号
if (!IsMatch(StrList, "^[/u4e00-/u9fa5]+$"))
{
if (CharType != 0)
result += Spc + StrList;
else
result += StrList;
CharType = 3;
}
else //中文
{
result += StrList;
CharType = 2;
}
}
//end if No.1

}//exit for
//
return result;
}
#endregion
//
#region 分词
/// <summary>
/// 分词
/// </summary>
/// <param name="key">关键词</param>
/// <returns></returns>
private static ArrayList StringSpliter(string[] key, string dictfile)
{
ArrayList List = new ArrayList();
try
{
SortedList dict = LoadDict(dictfile);//载入词典
//
for (int i = 0; i < key.Length; i++)
{
if (IsMatch(key[i], @"^(?!^/.$)([a-zA-Z0-9/./u4e00-/u9fa5]+)$")) //中文、英文、数字
{
if (IsMatch(key[i], "^[/u4e00-/u9fa5]+$"))//如果是纯中文
{
int keyLen = key[i].Length;
if (keyLen < 2)
continue;
else if (keyLen <= 7)
List.Add(key[i]);
//开始分词
for (int x = 0; x < keyLen; x++)
{
//x：起始位置//y：结束位置
for (int y = x; y < keyLen; y++)
{
string val = key[i].Substring(x, keyLen - y);
if (val == null || val.Length < 2)
break;
else if (val.Length > 10)
continue;
if (dict.Contains(val))
List.Add(val);
}
}
}
else if (!IsMatch(key[i], @"^(/.*)$"))//不全是小数点
{
List.Add(key[i]);
}
}
}
}
catch (Exception ex)
{
throw ex;
}
return List;
}
#endregion
//
#region 得到分词结果
/// <summary>
/// 得到分词结果
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public static string[] DoSplit(string key, string dictfile)
{
ArrayList KeyList = StringSpliter(FormatStr(key).Split(SplitChar.ToCharArray()), dictfile);
KeyList.Insert(0, key);
//去掉重复的关键词
for (int i = 0; i < KeyList.Count; i++)
{
for (int j = 0; j < KeyList.Count; j++)
{
if (KeyList[i].ToString() == KeyList[j].ToString())
{
if (i != j)
{
KeyList.RemoveAt(j); j--;
}
}
}
}
return (string[])KeyList.ToArray(typeof(string));
}
/// <summary>
/// 得到分词关键字，以逗号隔开
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public static string GetKeyword(string key, string dictfile)
{
string _value = "";
string[] _key = DoSplit(key, dictfile);
for (int i = 1; i < _key.Length; i++)
{
if (i == 1)
_value = _key[i].Trim();
else
_value += "," + _key[i].Trim();
}
return _value;
}
#endregion
}
}