在 C# 中读取 .txt 文件时出现问题，从（在立即空整行之后）到（下一个空整行）

Question

我正在尝试随机读取一个巨大的 .txt 文件。它有大量的段落，由一整行空白 space 和每个段落 post 分隔。我希望每次我随机阅读它时，它都会拉出一个完整的完整段落，为了上下文而不会遗漏任何字符或单词。我提前感谢您的帮助。

我添加了一个 for 循环只是为了测试它，看看我是否可以在某个时候包括一种连续识别运行空 space 的方法。那只会起作用 post 如果应用的话，显然已经选择了起点。

public static string GetRandomLine(string filename)
{        
    var lines = File.ReadAllLines(filename);
    var lineNumber = _rand.Next(0, lines.Length);
    string reply = lines[lineNumber];


    return reply ;
}

Answer 1

获得完整的段落

public static string GetRandomParagraph(string fileName)
{
    /* 
       Rather than reading all the lines, read all the text
       this gives you the ability to split by paragraph
    */
    var allText = File.ReadAllText(fileName);
    // Use as separator for paragraphs
    var paragraphSeparator = $"{Environment.NewLine}{Environment.NewLine}";
    // Treat large white spaces after a new line as separate paragraphs 
    allText = Regex.Replace(allText, @"(\n\s{3,})", paragraphSeparator);
    // Split the text into paragraphs
    var paragraphs = allText.Split(paragraphSeparator);
    // Get a random index between 0 and the amount of paragraphs
    var randomParagraph = new Random().Next(0, paragraphs.Length);

    return paragraphs[randomParagraph];
}

Answer 2

// This builds a list of Paragraph first
public static List<string> GetParagraphs(string filename)
{        
    var paragraphs = new List<string>();
    var lines = File.ReadAllLines(filename);
    bool newParagraph = true;
    string CurrentParagraph = string.Empty;
    // Build the list of paragraphs by adding to the currentParagraph until empty lines and then starting a new one
    foreach(var line in lines)
    {
        if(newParagraph)
        {
            CurrentParagraph = line;
            newParagraph = false;
        }
        else
        {
            if(string.IsNullOrWhiteSpace(line))// we're starting a new paragraph, add it to the list of paragraphs and reset current paragraph for next one
            {
                paragraphs.Add(CurrentParagraph);
                CurrentParagraph = string.Empty;
                newParagraph = true;
            }
            else // we're still in the same paragraph, add the line to current paragraph
            {
                newParagraph += (Environment.NewLine + line);
            }
        }
    }
    // Careful, if your file doesn't end with a newline the last paragraph won't count as one, in that case add it manually here.
}

public static Random rnd = new Random();

// And this returns a random one
public static string GetRandomParagraph(string fileName)
{
     var allParagraphs = GetParagraphs(filename);
     allParagraphs[rnd.Next(0,allParagraphs.length-1)]; // pick one of the paragraphs at random, stop at length-1 as collection indexers are 0 based    
}

请注意，如果您总是从同一个文件中读取数据，只需调用一次 GetParagraphs 并将段落列表保存在内存中，速度可能会快得多。

Answer 3

试试这个：

public static string GetRandomLine(string filename)
    {
        var lines = File.ReadAllLines(filename);
        var lineNumber = _rand.Next(0, lines.Length - 1);
        var blankBefore = lineNumber;
        var blankAfter = lineNumber + 1;
        string reply = "";

        while (lines[blankBefore].Length > 0)
        {
            blankBefore--;
        }

        while (lines[blankAfter].Length != 0)
        {
            blankAfter++;
        }

        for ( int i = blankBefore + 1; blankBefore < blankAfter; blankBefore++)
        {
            reply += lines[i];
        }
        return reply;
    }

根据您的描述，我假设文件以一个空行开始和结束。通过将随机行的独占上限设置为比行的长度小一，可以避免随机行成为文件最后一行的可能性。如果随机行是空行，blankBefore 将是该行的索引，否则，将回溯直到到达前一个空行。 blankAfter 作为随机行之后的下一行的索引开始，如果该行不是空白，则 blankAfter 增加直到它是下一个空白行的索引。

获得目标段落前后空行的索引后，只需在它们之间添加空行即可回复。

如果文件的第一行和最后一行不是空白，您需要验证 blankBefore 和 blankAfter 是否在数组的范围内。

Answer 4

尝试以下操作：

        public static string[] GetRandomParagraph(string filePath)
        {
            if (File.Exists(filePath))
            {
                string text = File.ReadAllText(filePath);
                string[] paragraphs = text.Split(new string[] { "\n\n" }, StringSplitOptions.None);
                return paragraphs[new Random().Next(0, paragraphs.Length)].Split('\n');

            }
            else
                throw new FileNotFoundException("The file was not found", filePath);
        }

我真的希望这就是您要找的。

Answer 5

我对@TheCoderCrab 上面提供的代码做了一些修改。我将该方法转换为字符串方法，因此它会 return 一个字符串。我只是添加了一个 for 循环，将段落数组的所有字符追加到一个新字符串，该字符串 return 将它添加到主字符串中。谢谢。

public static string GetRandomParagraph(string filePath)
    {
        if (File.Exists(filePath))
        {
            string text = File.ReadAllText(filePath);
            string[] paragraphs = text.Split(new string[] { "\n\n" }, StringSplitOptions.None);
            string [] paragraph = paragraphs[new Random().Next(0, paragraphs.Length)].Split('\n');

            //Added a for loop to build the string out of all the characters in the 'paragraph' array index.
            string pReturn = "";
            for (int a = 0; a < paragraph.Length; a++)
            {
                //Loop through and consecutively append each character of mapped array index to a return string 'pReturn'
                pReturn = pReturn + paragraph[a].ToString();
            }

            return pReturn;

        }
        else
            throw new FileNotFoundException("The file was not found", filePath);
    }

在 C# 中读取 .txt 文件时出现问题，从（在立即空整行之后）到（下一个空整行）

problem reading .txt file in C# starting from (after immediate empty whole line) to (the next empty whole line)

.net

c#

random

filereader

visual-studio