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   源码介绍

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可直接拿来测试哦

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

namespace Test.TFIDF
{
    class IF_IDF
    {
        /// <summary>
        /// 获取拆分后的词组以及每个词的出现次数
        /// </summary>
        /// <param name="text"></param>
        /// <returns></returns>
        public Dictionary<string, int> GetWordsFrequnce(string text)
        {
            
            Dictionary<string, int> dictionary = new Dictionary<string, int>();
            Regex regex = new Regex(@"[\u4e00-\u9fa5]");//分拣出中文字符
            MatchCollection results = regex.Matches(text);
            int temp;
            foreach (Match word in results)
            {
                if (dictionary.TryGetValue(word.Value, out temp))
                {
                    temp  ;
                    dictionary.Remove(word.Value);
                    dictionary.Add(word.Value, temp);
                }
                else
                {
                    dictionary.Add(word.Value, 1);
                }
            }
            return dictionary;
        }
        /// <summary>
        /// 文档中出现次数最多的词的出现次数
        /// </summary>
      
        /// <param name="wordsfre">拆分后的词组字典</param>
        /// <returns></returns>
        public int MaxWordFrequence( Dictionary<string, int> wordsfre)
        {
            Dictionary<string, int>.ValueCollection values = wordsfre.Values;
            int maxfre = 0;
            foreach (int value in values)
            {
                if (maxfre < value)
                {
                    maxfre = value;
                }
            }
            return maxfre;
        }
        /// <summary>
        /// 计算某词的IF，返回结果
        /// </summary>
        /// <param name="wordFre"></param>
        /// <param name="maxFre"></param>
        /// <returns></returns>
        public double[] TF(string text)
        {
            Dictionary<string, int> dictionary = GetWordsFrequnce(text);
            int maxFre = MaxWordFrequence(dictionary);
            double[] tf = new double[dictionary.Keys.Count];
            //for (int i=0; i< wordFre.Length; i  )
            //{
            //    tf[i] = wordFre[1] / maxFre;
            //}
            Dictionary<string,int>.ValueCollection values=dictionary.Values;
            int flag = 0;
            foreach(int Fre in values)
            {
                tf[flag] = Fre / maxFre;
                flag  ;

            }
            return tf;
        }
        /// <summary>
        /// 计算逆向词频，返回结果
        /// </summary>
        /// <param name="word"></param>
        /// <param name="text"></param>
        /// <returns></returns>
        public  double[] IDF(string text,string []texts)
        {
            Dictionary<string, int> dictionary = GetWordsFrequnce(text);
            double[] idf = new double[dictionary.Keys.Count];
            //int total_file = text.Length;//文件总数
            int []file_num = new int[dictionary.Keys.Count];            //含有该词组的文件数
            int flag = 0;
            foreach(string word in dictionary.Keys)
            {
                file_num[flag] = 0;
                for (int j=0; j < texts.Length; j  )
                {
                    if (texts[j].Contains(word))
                    {
                        file_num[flag]  ;
                    }
                }
                idf[flag] = Math.Log( texts.Length / file_num[flag],2) 1;
                flag  ;
            }
            
            return idf;

        }
        /// <summary>
        /// 计算所有文档中的词组的权重
        /// </summary>
        /// <param name="texts"></param>
        /// <returns></returns>
        public double [][]TF_IDF(string []texts)
        {
            double[][] tf_idf=new double[texts.Length][];
            for (int i=0; i< texts.Length; i  )
            {
                double[] tf = TF(texts[i]);
                double[] idf = IDF(texts[i], texts);
                tf_idf[i] = new double[tf.Length];
                for (int j = 0; j < tf.Length; j  )
                {
                    tf_idf[i][j] = tf[j] * idf[j];
                }
            }

                return tf_idf;
        }
        /// <summary>
        /// 通过传入所有文档以及要比较的两份文档的索引，计算相似度，返回结果
        /// </summary>
        /// <param name="i">第i份文档</param>
        /// <param name="j">第j份文档</param>
        /// <param name="texts"></param>
        /// <returns></returns>
        public double Similarity(int i, int j,string []texts)
        {
            
            double[][] tf_idf =TF_IDF( texts);
            double sum=0;  //两向量内积
            double i_length=0; //两向量模长
            double j_length = 0;
            //计算内积
            for (int m = 0; m < tf_idf[i-1].Length;m   )
            {
                if (m >= tf_idf[j-1].Length)
                {
                    break;
                }
                sum  = tf_idf[i-1][m] * tf_idf[j-1][m];
            }
            //第i份文档的向量模长
            for (int n = 0; n < tf_idf[i-1].Length; n  )
            {
                i_length  = tf_idf[i-1][n] * tf_idf[i-1][n];
            }
            i_length = Math.Sqrt(i_length);
            // 第j份文档的向量模长
            for (int n = 0; n < tf_idf[j-1].Length; n  )
            {
                j_length  = tf_idf[j-1][n] * tf_idf[j-1][n];
            }
            j_length = Math.Sqrt(j_length);
            //夹角余弦值计算公式，两向量内积除以两向量的模长乘积
            return sum / (i_length * j_length);

        }

    }
}