How to sort numbers between two markers in a text file

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VC#
I have a text file contains a pair of numbers spilted by comma and grouped by special markers
Like 1000, 2000 and 3000 serial no.
How can I sort these number according to the first column.

Here the Orginal text file named data.txt:

The sorted file should look like this:

What I have tried:

C#

StreamReader sr= new StreamReader(data.txt);
StreamWriter sw= new StreamWriter(soted.txt,true);

for(str=1000; str <= 3000; str += 1000)
{
  while((line = sr.ReadLine()) != null)
   {
        if line.Contains(str)
         {
              char[] sep = new char[]{','};
              string[] sArr = line.Split(sep);
              for(i=0; i < sArr.Length-1;i++)
               {
                    xArr[i] = Int32.Parse(sArr[0]);
                     yArr[i] = Int32.Parse(sArr[1]);
                      sw.WriteLine("  {0} {1},Convert.ToInt32(xArr[i].ToString(),Convert.ToInt32(yArr[i].ToString());
               }
         }
    }
}

Posted 1-Sep-20 23:45pm

essukki

Updated 2-Sep-20 13:13pm

CPallini

v2

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PIEBALDconsult · Accepted Answer · 2020-09-02T13:13:00

Very often, when dealing with text, you will find that Regular Expressions will do a lot of the heavy lifting for you.

C#

public static string
    SortNumberList
    (
      string Input
    )
    {
      System.Text.StringBuilder result = new System.Text.StringBuilder ( Input.Length ) ;

      foreach 
      ( 
        System.Text.RegularExpressions.Match m 
      in
        System.Text.RegularExpressions.Regex.Matches 
        ( 
          Input 
        , 
          @"(^|\G)(?'Segment'(?'Marker'(\r\n)?\s*\d+\s*)(?'Pair'\r\n\s*(?'Neg'-?)\s*(?'Key'\d+)\s*,\s*(?'Value'\d+)\s*(?=(\r\n)))*(?=(\r\n)))" 
        )
      )
      {
        result.Append ( m.Groups [ "Marker" ].Value ) ;

        System.Collections.Generic.List<System.Tuple<int,System.Text.RegularExpressions.Capture>> lis =
          new System.Collections.Generic.List<System.Tuple<int,System.Text.RegularExpressions.Capture>> 
          ( m.Groups [ "Pair" ].Captures.Count ) ;

        for ( int i = 0 ; i < m.Groups [ "Pair" ].Captures.Count ; i++ )
        {
          int k = System.Int32.Parse ( m.Groups [ "Key" ].Captures [ i ].Value ) ;

          if ( m.Groups [ "Neg" ].Captures [ i ].Value.Length > 0 )
          {
            k *= -1 ;
          }

          lis.Add ( new System.Tuple<int,System.Text.RegularExpressions.Capture> ( k , m.Groups [ "Pair" ].Captures [ i ] ) ) ;
        }

        lis.Sort() ;

        for ( int i = 0 ; i < lis.Count ; i++ )
        {
          result.Append ( lis [ i ].Item2 ) ;
        }
      }

      return ( result.ToString() ) ;    
    }

OriginalGriff · Accepted Answer · 2020-09-02T00:36:00

Store the numbers in a tuple or a struct / class instead of two arrays: it makes si=orting a whole load easier.
Using a class is simple:

C#

public class TwoInts
    {
    public int One { get; set; }
    public int Two { get; set; }
    }

C#

TwoInts[] arr = new TwoInts[100];
// Read your file, get each line in the section into two integers x and y
...
arr[i] = new TwoInts() { One = x, Two = y };
...
// Then sort them
arr = arr.OrderBy(v => v.One).ToArray();

I'd probably use a List instead of an array.

CPallini · Accepted Answer · 2020-09-02T01:11:00

Try (modify it according to your exact requirements):

C#

public static void Main(string[] args)
		{
			var info = new  SortedList<int , SortedList<int, int>>();

			using (var sr = new System.IO.StreamReader("data.txt") )
			{
				
				int serial_no=0;
				
				while ( sr.Peek() >= 0)
				{
					string line = sr.ReadLine();
					string [] items = line.Split(new char [] {','});
					if (items.Length == 1)
					{
						serial_no = int.Parse(items[0]);
						info.Add(serial_no, new SortedList<int, int>());
					}
					else if (items.Length == 2)
					{
						info[serial_no].Add(int.Parse(items[0].Replace(" ", string.Empty)), int.Parse(items[1].Replace(" ", string.Empty)));
					}
					else
						throw new Exception(string.Format("invalid line {0}", line));
				}
			}
			foreach (var element in info) 
			{
				Console.WriteLine(element.Key);
				foreach (var p in element.Value)
					Console.WriteLine(string.Format("{0}, {1}", p.Key, p.Value));
			}	
			
		}

Maciej Los · Accepted Answer · 2020-09-02T01:33:00

I'd create a class (as OriginalGriff mentioned) but different way:

C#

public class MyData
{
	
	public MyData(string _header)
	{
		header = Int32.Parse(_header);
	}

	public int header = 0;
	public List<Tuple<int, int>> data = new List<Tuple<int, int>>(); 
}

Usage:

C#

//read original file
string[] lines  = File.ReadAllLines("originalfilename.txt");

List<MyData> mdlist = new List<MyData>();
int i = 0;
MyData md = null;
while(i<lines.Count())
{
    string line = lines[i];
    string[] parts = line.Split(new string[]{", ", " ,", ","}, StringSplitOptions.RemoveEmptyEntries);
    if(parts.Length==0) break;
    if(parts.Length==1)
    {
        //parts[0].Dump();
        md = new MyData(parts[0]);
        mdlist.Add(md);
    }
    else
    {
        parts[0] = parts[0].Replace(" ", null);
        parts[1] = parts[1].Replace(" ", null);
        md.data.Add(new Tuple<int, int>(Int32.Parse(parts[0]), Int32.Parse(parts[1])));
    }
    i++;
}

i =0;
foreach(MyData m in mdlist)
{
    i++;
    lines[i] = m.header.ToString();
    foreach(var d in m.data.OrderBy(x=>x.Item1))
    {
        lines[i] = string.Join(",", d);
        i++;
    }
}
//save new file
File.WriteAllLines("newfilename.txt", lines);

For further details, please see:
File.ReadAllLines Method (System.IO) | Microsoft Docs[^]
File.WriteAllLines Method (System.IO) | Microsoft Docs[^]

George Swan · Accepted Answer · 2020-09-02T06:27:00

Read All Lines from the file. Then Split the lines on the commas. Foreach line do the following

Fix the incorrect formatting of negative numbers, remove the space between the minus sign and the number
Build a value tuple (int Group, int FirstItem, int SecondItem) using int.Parse.
Add the tuple to a List of value tuples.

Finally, use Linq to Sort the tuple list on Group then by FirstItem and output the list. Something like this:

C#

public static void Main(string[] args)
 {
   List<(int Group, int First, int Second)> tuples = new List<(int Group, int First, int Second)>();
   var lines = File.ReadAllLines(@"C:\Temp\Orig.txt");
   int groupId = -1;
   foreach (var l in lines)
    {
     //Need to fix the faulty formatting of negative numbers, leading and trailing spaces are acceptable
     // It's the space between the minus sign and the number that blows the fuse.
      var line = l.Replace("- ", "-");
      string[] items = line.Split(',');
      if (items.Length > 2) throw new FormatException($"Invalid data: {line}");
       // need to check for Null or Empty as items.Length is never 0
       //because the default is to set [0] to the original string
      if (items.Length == 1 && !string.IsNullOrEmpty(items[0]))//its a group marker,empty lines are ignored
         {
           groupId = int.Parse(items[0]);
         }
      if (items.Length == 2)
         {
           tuples.Add((groupId, int.Parse(items[0]), int.Parse(items[1])));
         }

     }
      var sorted = tuples.OrderBy(t => t.Group).ThenBy(t => t.First);
      int group = -1;
      foreach (var (Group, First, Second) in sorted)
       {
         if (Group != group)
          {

            group = Group;
            Console.WriteLine(group);
           }
           Console.WriteLine($"{First}, {Second}");

       }
          Console.ReadLine();

   }

How to sort numbers between two markers in a text file

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