How to parse specific line in a text file in c#

Question

I need to parse a specific lines in a text file in which to begin by a specific words as in the following image :

I need to parse the lines that begins by "Level" only and extract the value of "Row" and "Col" only. Note that the text file will contain 6 groups of such data where each group starts by

---------------- chromosome : # ------------------

See the following sample : Sample

I need to save each group's row and columns in a separated list for each!!. Is there any way to perform this ?

I tried the following method :

public List<int[,]> getValuesFromTextFile(String filePath ) {

     IEnumerable<string> allLines = Enumerable.Empty<string>();

     List<int[,]> path = new List<int[,]>();

     int[,] item = new int[2,1];

    if (File.Exists(filePath))

        {
                    //Read all content of the files and store it to the list split with new line 
                    allLines = File.ReadLines(filePath);
        }
 
                    //all Level lines
                IEnumerable<string> levelLines = allLines.Where(d => d.StartsWith("Level", StringComparison.CurrentCultureIgnoreCase));
 
                foreach(string line in levelLines)

                {
                     string[] values= line.Split(':');//either space or tab or others as your file contain seperator  

                     for(int i=1; i <values.Length;i++)  {

                     string value = values[i];// skip index 0,it contains label, remaining are point data

                     if (i == 3) item[1,0] = Int32.Parse(value);

                     if (i == 5 && item[1,0] != null ) { item[0,0] = Int32.Parse(value);
                          path.Add(item);

                          }

                 }

        }



                return path;

        }

I got the following error at line( if (i == 3) item[1,0] = Int32.Parse(value); ) :

Input string was not in a correct format.

When I put a break point at this line I saw that the value of string "value" equal to null!!.

When I added a break point to see all lines list contents, I got as in the following image :

The above method needs to parse each group of levels separately!!.

Answer 1

You can use a named group Regex to parse the lines and build out a list of records.

void Main()
{
    var file = File.ReadLines(@"C:\TreeParser.txt");

    var groupRegex = new Regex(@"Chromosome : (?<Chromosome>[0-9])");
    var recordRegex = new Regex(@"Level : '(?<Level>[0-9])', Row : '(?<Row>[0-9])', Col : '(?<Col>[0-9])'");

    var groups = new List<Group>();

    foreach (var line in file)
    {
        var groupMatch = groupRegex.Match(line);
        if (groupMatch.Success)
        {
            groups.Add(new Group
            {
                Chromosome = int.Parse(groupMatch.Groups["Chromosome"].Value),
                Records = new List<Record>()
            });
        }

        var recordMatch = recordRegex.Match(line);
        if (!recordMatch.Success)
        {
            // No match was found
            continue;
        }

        var level = new Record
        {
            Level = int.Parse(recordMatch.Groups["Level"].Value),
            Row = int.Parse(recordMatch.Groups["Row"].Value),
            Col = int.Parse(recordMatch.Groups["Col"].Value)
        };

        groups.Last().Records.Add(level);
    }

    // groups now contains a list of each section from the file with a list of records
}

public class Record
{
    public int Level { get; set; }
    public int Row { get; set; }
    public int Col { get; set; }
}

public class Group
{
    public int Chromosome { get; set; }
    public List<Record> Records { get; set; }
}