关键词提取算法-搜索引擎技术代码实例。该算法由C#编写，采用经典的TF-IDF权重公式计算并确定关键词，对研究搜索引擎的初学者有较大帮助。-Keywords extraction algorithm- Code examples of search engine technology. The algorithm from C# to prepare, using the classical TF-IDF weighting formula and to identify words.

tf–idf, short for term frequency–inverse document frequency, is a numerical statistic that is intended to reflect how important a word is to a document in a collection or corpus.[1]:8 It is often used as a weighting factor in information retrieval an

1-The Cranfield collection is a standard IR text collection(included in this directory)., consisting of 1400 documents the aerodynamics field.Write a program that preprocesses the collection.Determine the frequency of occurence for all the words in t