我需要在大约120个文本文件中找到一些文本,我想知道哪个是搜索文本的最佳和最快的方式。我应该读取RichTextBox中的每个文件,然后使用其方法搜索文本,还是应该将这些文件读入字符串变量然后使用正则表达式进行搜索?
我认为性能背后的主要因素是找到一种方法,这样就不需要遍历已经过测试匹配的行。有没有办法一次性找到文件中的所有匹配项?有没有人知道如何在Visual Studio中找到文本文件中的匹配?它在大约800-1000毫秒内搜索了200个文本文件以进行匹配。我认为它使用多个线程来实现这一目标。
答案 0 :(得分:2)
根据您的描述(120个文件,70K-80K字,每个文件1-2 MB),最好的方法是读取文件一次并构建可搜索的索引。我在下面举了一个例子来说明如何完成这样的事情,但是如果你需要更复杂的搜索词匹配而不是找到一个确切的术语或一个前缀术语,那么这对你来说可能是有限的。
如果您需要更复杂的文本搜索匹配(同时获得良好的性能),我建议您查看专门为此目的而构建的优秀Lucene库。
public struct WordLocation
{
public WordLocation(string fileName, int lineNumber, int wordIndex)
{
FileName = fileName;
LineNumber = lineNumber;
WordIndex = wordIndex;
}
public readonly string FileName; // file containing the word.
public readonly int LineNumber; // line within the file.
public readonly int WordIndex; // index within the line.
}
public struct WordOccurrences
{
private WordOccurrences(int nOccurrences, WordLocation[] locations)
{
NumberOfOccurrences = nOccurrences;
Locations = locations;
}
public static readonly WordOccurrences None = new WordOccurrences(0, new WordLocation[0]);
public static WordOccurrences FirstOccurrence(string fileName, int lineNumber, int wordIndex)
{
return new WordOccurrences(1, new [] { new WordLocation(fileName, lineNumber, wordIndex) });
}
public WordOccurances AddOccurrence(string fileName, int lineNumber, int wordIndex)
{
return new WordOccurrences(
NumberOfOccurrences + 1,
Locations
.Concat(
new [] { new WordLocation(fileName, lineNumber, wordIndex) })
.ToArray());
}
public readonly int NumberOfOccurrences;
public readonly WordLocation[] Locations;
}
public interface IWordIndexBuilder
{
void AddWordOccurrence(string word, string fileName, int lineNumber, int wordIndex);
IWordIndex Build();
}
public interface IWordIndex
{
WordOccurrences Find(string word);
}
public static class BuilderExtensions
{
public static IWordIndex BuildIndexFromFiles(this IWordIndexBuilder builder, IEnumerable<FileInfo> wordFiles)
{
var wordSeparators = new char[] {',', ' ', '\t', ';' /* etc */ };
foreach (var file in wordFiles)
{
var lineNumber = 1;
using (var reader = file.OpenText())
{
while (!reader.EndOfStream)
{
var words = reader
.ReadLine()
.Split(wordSeparators, StringSplitOptions.RemoveEmptyEntries)
.Select(f => f.Trim());
var wordIndex = 1;
foreach (var word in words)
builder.AddWordOccurrence(word, file.FullName, lineNumber, wordIndex++);
lineNumber++;
}
}
}
return builder.Build();
}
}
然后,最简单的索引实现(只能进行精确匹配查找)在内部使用字典:
public class DictionaryIndexBuilder : IIndexBuilder
{
private Dictionary<string, WordOccurrences> _dict;
private class DictionaryIndex : IWordIndex
{
private readonly Dictionary<string, WordOccurrences> _dict;
public DictionaryIndex(Dictionary<string, WordOccurrences> dict)
{
_dict = dict;
}
public WordOccurrences Find(string word)
{
WordOccurrences found;
if (_dict.TryGetValue(word, out found);
return found;
return WordOccurrences.None;
}
}
public DictionaryIndexBuilder(IEqualityComparer<string> comparer)
{
_dict = new Dictionary<string, WordOccurrences>(comparer);
}
public void AddWordOccurrence(string word, string fileName, int lineNumber, int wordIndex)
{
WordOccurrences current;
if (!_dict.TryGetValue(word, out current))
_dict[word] = WordOccurrences.FirstOccurrence(fileName, lineNumber, wordIndex);
else
_dict[word] = current.AddOccurrence(fileName, lineNumber, wordIndex);
}
public IWordIndex Build()
{
var dict = _dict;
_dict = null;
return new DictionaryIndex(dict);
}
}
用法:
var builder = new DictionaryIndexBuilder(EqualityComparer<string>.Default);
var index = builder.BuildIndexFromFiles(myListOfFiles);
var matchSocks = index.Find("Socks");
如果您还想进行前缀查找,请实现使用排序字典的索引构建器/索引类(并更改IWordIndex.Find
方法以返回多个匹配项,或者向接口添加新方法以查找部分字段/模式匹配)。
如果你想进行更复杂的查找,请选择Lucence。
答案 1 :(得分:0)
如果我在哪里,我会在哪里:
1-我将所有文件路径加载到字符串列表。
2-我将创建一个新列表来存储与我的搜索词匹配的文件路径。
3-我将在“文件”列表中循环foreach并搜索我的术语,然后我将匹配的文件添加到新列表中。
string searchTerm = "Some terms";
string[] MyFilesList = Directory.GetFiles(@"c:\txtDirPath\", "*.txt");
List<string> FoundedSearch=new List<string>();
foreach (string filename in MyFilesList)
{
string textFile = File.ReadAllText(filename);
if (textFile.Contains(searchTerm))
{
FoundedSearch.Add(filename);
}
}
然后你可以处理List:FoundedSearch你想要什么。
顺便说一下:
我不知道最好的答案,但性能将非常好,直到800文本文件,每个文件1000字 您可以使用this chart
很好地找到效果答案 2 :(得分:0)
我假设你需要在每个文件中搜索相同的字符串。您可以为每次搜索使用compiled regex
。
string searchTerm = "searchWord";
Regex rx = new Regex(String.Format("\b{0}\b", searchTerm), RegexOptions.Compiled);
List<string> filePaths = new List<string>();
foreach (string filePath in filePaths)
{
string allText = File.ReadAllText(filePath);
var matches = rx.Matches(allText);
//rest of code
}
你必须对性能进行基准测试,但我认为主要的瓶颈是从磁盘打开和读取文件。如果情况确实如此,您可以查看Memory-Mapped Files。或者,根据您最终要做的事情,Lucene.Net
(如评论中提到的I4V)这样的专用文本搜索器可能更适合。