We Keep Coding

C# Read file, split at ; write in array

so I have a file like this:
1;2;5
1;3;3
1;4;3
1;5;1
1;6;0
and I want every number as easy accassible as possibe
so I thought multi dimentional array
that's the idea so far:
System.IO.StreamReader file = new System.IO.StreamReader(#"C:\Users\Hisfantor\Desktop\transport.txt");
int count = 0;
string linee;
string line;
string[] extract;
while ((linee = file.ReadLine()) != null)
{
count++;
}
textBox1.Text = Convert.ToString(count);
double[,] destinations = new double[(int)count, 3];
for (int i = 0; i < count; i++)
{
line = file.ReadLine();
extract = line.Split(';');
destinations[i, 1] = Convert.ToDouble(extract[0]);
destinations[i, 2] = Convert.ToDouble(extract[1]);
destinations[i, 3] = Convert.ToDouble(extract[2]);
listBox1.Items.Add(destinations[i, 1]);
}
file.Close();
I tried different things, but never get anything in the listbox(just for testing)

Try this:
using System.IO.StreamReader file = new System.IO.StreamReader(#"C:\Users\Hisfantor\Desktop\transport.txt");
int count = 0;
string line;
string[] extract;
while ((line = file.ReadLine()) != null)
{
extract = line.Split(';');
var lineValue = new LineValue()
{
Col1 = Convert.ToDouble(extract[0]),
Col2 = Convert.ToDouble(extract[1]),
Col3 = Convert.ToDouble(extract[2]),
};
listBox1.Items.Add(lineValue);
count++;
}
textBox1.Text = Convert.ToString(count);
public class LineValue
{
public double Col1 { get; set; }
public double Col2 { get; set; }
public double Col3 { get; set; }
public override string ToString() => $"{Col1};{Col2};{Col3}";
}

I suggest jagged array, i.e. array of array double[][] instead of 2D one (double[,]). Then you can query the file with a help of Linq:
using System.Linq;
...
double[][] destinations = File
.ReadLines(#"C:\Users\Hisfantor\Desktop\transport.txt")
.Where(line => !string.IsNullOrWhiteSpace(line))
.Select(line => line
.Split(';')
.Select(item => double.Parse(item))
.ToArray())
.ToArray();
foreach (var array in destinations)
listBox1.Items.Add(array[1]);

This is how I would approach it.
class Item
{
public int Value1 { get; set; }
public int Value2 { get; set; }
public int Value3 { get; set; }
}
string line;
List<Item> items = new List<Item>();
using (StreamReader reader = new StreamReader(path))
{
while ((line = reader.ReadLine()) != null)
{
string[] tokens = line.Split(';');
if (tokens.Length == 3)
{
int value;
Item item = new Item();
item.Value1 = int.TryParse(tokens[0], out value) ? value : 0;
item.Value2 = int.TryParse(tokens[1], out value) ? value : 0;
item.Value3 = int.TryParse(tokens[2], out value) ? value : 0;
items.Add(item);
}
}
}
This code reads a line at a time and populates a list of Items as it reads them. It includes error checking to avoid unexpected exceptions due to invalid inputs.
Also, you should wrap StreamReader in a using block to ensure it cleans up in a timely manner, even if an exception exits your method prematurely.

How to write Efficiently write Large 2D arrays to CSV file

EDIT: Using the solution provided, I was able to get it to work (not the most efficient but it works) using the following:
public static void WriteArray(object[,] dataArray, string filePath, bool deleteFileIfExists = true)
{
if (deleteFileIfExists && File.Exists(filePath))
{
File.Delete(filePath);
}
byte columnCount = (byte) dataArray.GetLength(1);
int rowCount = dataArray.GetLength(0);
for(int row = ReadExcel.ExcelIndex; row <= rowCount; row++)
{
List<string> stringList = new List<string>();
for(byte column = ReadExcel.ExcelIndex; column <= columnCount; column++)
{
stringList.Add(dataArray[row, column].ToString());
}
string rowAsString = StringifyRow(stringList.ToArray());
WriteLine(filePath, rowAsString);
}
}
public static string StringifyRow(string[] row)
{
return string.Join(",", row);
}
public static void WriteLine(string filePath, string rowAsString)
{
using (StreamWriter writer = new StreamWriter(filePath, append: true))
{
writer.WriteLine(rowAsString);
writer.Flush();
}
}
I am working on a data consolidation application. This app will read in data as 2D arrays, manipulate some of the columns in memory, consolidate arrays, then write to a csv file.
I am working on a test method of writing to CSV. Currently my array is just over 70K rows and 29 columns. In production, it will always be at least 4 times as many rows. For the test, I did not consolidate any arrays. This is just from one data source.
In order to write to CSV, I have tried numerous methods:
Pass the array (object[,]) to a helper method that loops through each row, creates a string from the values, then appends the string to a list, finally passes the list to the csvwriter to write the list of strings to a file. I get OutOfMemory errors when creating the list of strings.
The same as above but with StringBuilder and no List, just a giant string with stringbuilder (found on .netperls) - same error - OutofMemory exception
No helper method, just pass the array to the csvwriter method, loop through each row, build a string (I've tried this with string builder as well) and write each line one by one to the file. I get an OutOfMemory exception.
Some of my code (some various methods have been commented out) is below:
using System.IO;
using System.Text;
using System.Collections.Generic;
namespace ExcelIO
{
public static class CsvWriter
{
public static void WriteStringListCsv(List<string> data, string filePath, bool deleteIfExists = true)
{
if (deleteIfExists && File.Exists(filePath))
{
File.Delete(filePath);
}
//foreach(string record in data)
//{
// File.WriteAllText(filePath, record);
//}
using (StreamWriter outfile = new StreamWriter(filePath))
{
foreach (string record in data)
{
//trying to write data to csv
outfile.WriteLine(record);
}
}
}
public static void WriteDataArrayToCsv(List<string> data, string filePath, bool deleteIfExists = true)
{
if (deleteIfExists && File.Exists(filePath))
{
File.Delete(filePath);
}
//foreach(string record in data)
//{
// File.WriteAllText(filePath, record);
//}
//using (StreamWriter outfile = new StreamWriter(filePath))
//{
// File.WriteAllText(filePath, )
//}
using (StreamWriter outfile = new StreamWriter(filePath))
{
foreach(string record in data)
{
outfile.WriteLine(record);
}
}
}
public static List<string> ConvertArrayToStringList(object[,] dataArray, char delimiter=',', bool includeHeaders = true)
{
List<string> dataList = new List<string>();
byte colCount = (byte)dataArray.GetLength(1);
int rowCount = dataArray.GetLength(0);
int startingIndex = includeHeaders ? ReadExcel.ExcelIndex : ReadExcel.ExcelIndex + 1;
//StringBuilder dataAsString = new StringBuilder();
for (int rowIndex = startingIndex; rowIndex <= rowCount; rowCount++)
{
StringBuilder rowAsString = new StringBuilder();
//string rowAsString = "";
for (byte colIndex = ReadExcel.ExcelIndex; colIndex <= colCount; colIndex++)
{
//rowAsString += dataArray[rowIndex, colIndex];
//rowAsString += (colIndex == colCount) ? "" : delimiter.ToString();
// Wrap in Quotes
rowAsString.Append($"\"{dataArray[rowIndex, colIndex]}\"");
if (colIndex == colCount)
{
rowAsString.Append(delimiter.ToString());
}
}
// Move to nextLine
//dataAsString.AppendLine();
//outfile.WriteLine(rowAsString);
dataList.Add(rowAsString.ToString());
}
//return dataAsString.ToString();
return dataList;
}
}
}
I've tried everything I've seen from searching online but everything gives me an OutOfMemroy exception when piecing together the rows (even just doing one row at a time and writing that). Is there a better way to efficiently and hopefully quickly write a large 2D array to a csv file?
Any and all tips are greatly appreciated.

With code like below I've never had any memory issues, even with huge data
class Program
{
static void Main(string[] args)
{
StreamWriter writer = new StreamWriter("Filename");
List<Record> data = new List<Record>();
foreach (Record record in data)
{
string line = string.Join(",", record.field1, record.field2, record.field3, record.field4, record.field5);
writer.WriteLine(line);
}
writer.Flush();
writer.Close();
}
}
public class Record
{
public string field1 { get; set; }
public string field2 { get; set; }
public string field3 { get; set; }
public string field4 { get; set; }
public string field5 { get; set; }
}

CSV-file values to List<List>

I have a CSV file that I want some values from. One problem is that I don't know how many columns the file has. The number can be different every time I get a new CSV file. It will always have columns and rows with values. I will get it from a normal excel-file.
I want the method to return a List<List>.
ListA(FirstName, LastName, PhoneNumber... and so on) here I don't know how many items ListA will have. It can be different every time.
Inside ListA I want lists of persons like this:
ListA[FirstName] = List1(Zlatan, Lionel, Anders.....)
ListA[LastName] = List2(Ibrahimovic, Messi, Svensson.....) .. and so on.

You could create a class Person
class person {
private string FirstName;
private string LastName;
// others
}
Open the File and split each row in the file with the String.Split()-Method then convert each value and create Objects, which you can add to a List.
List<Person> persons = new List<Person>();
persons.Add(personFromFile);
Thats a pretty short solution but it works
Edit: Variable Fields per Row
If thats the case you could use a List<string[]> stringArraylist; and then add the results of the String.Split()-Method to it.
List<string[]> stringArraylist;
stringArraylist = new List<string[]>();
stringArraylist.Add("Andrew;Pearson;...;lololo;".Split(';'));
Is that more of what you wanted?

There are a lot of questions on SO that deal with parsing CSV files. See here for one: Reading CSV files in C#. I am fairly certain there are some solutions built in to .NET, though I can't recall what they are at the moment. (#ZoharPeled suggested TextFieldParser)
Most of the parsing solutions with give you a collection of rows where each item is a collection of columns. So assuming you have something like a IEnumerable<IList<string>>, you could create a class and use LINQ queries to get what you need:
public class CSVColumns
{
public IEnumerable<IList<string>> CSVContents { get; private set; }
public CSVColumns(IEnumerable<IList<string>> csvcontents)
{
this.CSVContents = csvcontents;
}
public List<string> FirstNames
{
get { return GetColumn("FirstName"); }
}
public List<string> LastNames
{
get { return GetColumn("LastName"); }
}
/// <summary>
/// Gets a collection of the column data based on the name of the column
/// from the header row.
/// </summary>
public List<string> GetColumn(string columnname)
{
//Get the index of the column with the name
var firstrow = CSVContents.ElementAtOrDefault(0);
if (firstrow != null)
{
int index = -1;
foreach (string s in firstrow)
{
index++;
if (s == columnname)
{
return GetColumn(index, true);
}
}
}
return new List<string>();
}
/// <summary>
/// Gets all items from a specific column number but skips the
/// header row if needed.
/// </summary>
public List<string> GetColumn(int index, bool hasHeaderRow = true)
{
IEnumerable<IList<string>> columns = CSVContents;
if (hasHeaderRow)
columns = CSVContents.Skip(1);
return columns.Select(list =>
{
try
{
return list[index];
}
catch (IndexOutOfRangeException ex)
{
return "";
}
}
).ToList();
}
}

I finally got a solution and it's working for me. My friend made it so all creed to him. No user here on stackoverflow so I post it instead.
private List<Attributes> LoadCsv()
{
string filename = #"C:\Desktop\demo.csv";
// Get the file's text.
string whole_file = System.IO.File.ReadAllText(filename);
// Split into lines.
whole_file = whole_file.Replace('\n', '\r');
string[] lines = whole_file.Split(new char[] { '\r' },
StringSplitOptions.RemoveEmptyEntries);
// See how many rows and columns there are.
int num_rows = lines.Length;
int num_cols = lines[0].Split(';').Length;
// Allocate the data array.
string[,] values = new string[num_rows, num_cols];
// Load the array.
for (int r = 0; r < num_rows; r++)
{
string[] line_r = lines[r].Split(';');
for (int c = 0; c < num_cols; c++)
{
values[r, c] = line_r[c];
}
}
var attr = new List<Attributes>();
for (var r = 0; r < num_rows; r++)
{
if (r == 0)
{
for (var c = 0; c < num_cols; c++)
{
attr.Add(new Attributes());
attr[c].Name = values[r, c];
attr[c].Value = new List<String>();
}
}
else
{
for (var b = 0; b < num_cols; b++)
{
var input = values[r, b];
attr[b].Value.Add(input);
}
}
}
// Return the values.
return attr;
}

"Object reference not set to an instance of an object" error during the compilation

I get the "Object reference not set to an instance of an object" error when i compile the code at string[] values = lineuser.Split(' '); . Any idea?
namespace function
{
public partial class Form1 : Form
{
float userscore,itemscore,result;
string lineitem, lineuser;
//float[][] a = new float[89395][100];
//float[][] b = new float[1143600][100];
float[][] a = Enumerable.Range(0, 89395).Select(i => new float[100]).ToArray();
float[][] b = Enumerable.Range(0, 1143600).Select(j => new float[100]).ToArray();
//float[,] c = new float[89395, 100];
StreamReader fileitem = new StreamReader("c:\\ITEM_SVD_FULL.txt");
StreamReader fileuser = new StreamReader("c:\\USER_SVD_FULL.txt");
public Form1()
{
InitializeComponent();
for (int x = 0; x <= 8939500; x++)
{
lineuser = fileuser.ReadLine();
string[] values = lineuser.Split(' '); //<------the line's error
int userid, factoriduser;
foreach (string value in values)
{
userid = Convert.ToInt32(values[0]);
factoriduser = Convert.ToInt32(values[1]);
userscore = Convert.ToSingle(values[2]);
a[userid][factoriduser] = userscore;
}
}
for (int y = 0; y <= 114360000; y++)
{
lineitem = fileitem.ReadLine();
string[] valuesi = lineitem.Split(' ');
int itemid, factoriditem;
foreach (string value in valuesi)
{
itemid = Convert.ToInt32(valuesi[0]);
factoriditem = Convert.ToInt32(valuesi[1]);
itemscore = Convert.ToSingle(valuesi[2]);
b[itemid][factoriditem] = itemscore;
}
}
}
public float dotproduct(int userid,int itemid)
{
//get the score of 100 from user and item to dotproduct
float[] u_f = a[userid];
float[] i_f = b[itemid];
for (int i = 0; i <u_f.GetLength(1); i++)
{
result += u_f[userid] * i_f[itemid];
}
return result;
}
private void btn_recomm_Click(object sender, EventArgs e)
{
if(txtbx_id.Text==null)
{
MessageBox.Show("please insert user id");
}
if (txtbx_id.Text != null && txtbx_itemid==null)
{
int sc = Convert.ToInt32(txtbx_id.Text);
if (sc>=0 &&sc<=89395)
{
for (int z=0;z<=1143600;z++)
{
dotproduct(sc,z);
}
//Hashtable hashtable = new Hashtable();
//put the result in hashtable
//foreach (DictionaryEntry entry in hashtable)
//{
//Console.WriteLine("{0}, {1}", entry.Key, entry.Value);
// }
}
}
if (txtbx_id!=null &&txtbx_itemid!=null)
{
int uid = Convert.ToInt32(txtbx_id.Text);
int iid = Convert.ToInt32(txtbx_itemid.Text);
{
if (uid>=0 && uid<=89395 && iid>=0 && iid<=1143600)
{
dotproduct(uid,iid);
MessageBox.Show("The Score of user id "+uid+" is "+result);
}
}

Please check you lineuser variable is null
public Form1()
{
InitializeComponent();
for (int x = 0; x <= 8939500; x++)
{
if(!string.IsNullorEmpty(lineuser) //<--- check the string is empty
{
string[] values = lineuser.Split(' '); //<------the line's error
int userid, factoriduser;
foreach (string value in values)
{
userid = Convert.ToInt32(values[0]);
factoriduser = Convert.ToInt32(values[1]);
userscore = Convert.ToSingle(values[2]);
a[userid][factoriduser] = userscore;
}
}
}
for (int y = 0; y <= 114360000; y++)
{
lineitem = fileitem.ReadLine();
if(!string.IsNullorEmpty(lineitem) //<--- check the string is empty
{
string[] valuesi = lineitem.Split(' ');
int itemid, factoriditem;
foreach (string value in valuesi)
{
itemid = Convert.ToInt32(valuesi[0]);
factoriditem = Convert.ToInt32(valuesi[1]);
itemscore = Convert.ToSingle(valuesi[2]);
b[itemid][factoriditem] = itemscore;
}
}
}
}
Now you can avoid the error.

You haven't opened the Stream fileuser so it is still null.

It is really a bad practice to open the file while you define the global variable in your class.
But as part from this, when you call ReadLine the result could be a null because there are no more lines to read and you don't check for this case.
Looking at the code shown above, there is no need to have a global variable for the filestream, so, the usual pattern when handling resources (OPEN/USE/CLOSE) should be followed for both files
public Form1()
{
InitializeComponent();
string lineuser;
// OPEN
using(StreamReader fileuser = new StreamReader("c:\\USER_SVD_FULL.txt"))
{
// USE
while((lineuser = fileuser.ReadLine()) != null)
{
string[] values = lineuser.Split(' ');
....
}
} //CLOSE & DISPOSE
....
string lineitem;
using(StreamReader fileitem = new StreamReader("c:\\ITEM_SVD_FULL.txt"))
{
while((lineitem = fileitem.ReadLine()) != null)
{
string[] valuesi = lineitem.Split(' ');
....
}
}

Removing More Than Two Duplicates From A List

I'm trying to figure out the best way to remove duplicates from a list in C#. However I want to keep two of the duplicated entries (two total identical entries) while removing all of the rest. I've seen plenty of examples of removing all duplicates from a list, but my specific issue seems to be less common.
This is the majority of my code. The background is this is a debate scheduler project for a class I'm in. I research a few ways to delete duplicates and found many on here but not with my stipulations. Each team can only debate twice per day and no more and they are assigned randomly to there debate times leading to my problem of them being assigned more than two times per scheduled day.
The teams are being assigned randomly and then moved to a list, so by duplicates I mean I'm trying to remove all dupes after the initial two if they exist at all.
Thanks and sorry for the ambiguity.
namespace SWEProject3
{
public partial class DebateSchedulerForm : Form
{
//There are 10 slots for team names
//The names can only be edited by the superadmin
static int ADMIN = 1;
static int GUEST = 2;
public List<string> nameList = new List<string>();
public List<string> winList = new List<string>();
public List<string> lossList = new List<string>();
public List<string> dateList = new List<string>();
public List<string> debateList = new List<string>();
public List<string> week1List = new List<string>();
public List<string> week2List = new List<string>();
public List<string> week3List = new List<string>();
public List<string> week4List = new List<string>();
public List<string> week5List = new List<string>();
public List<string> week6List = new List<string>();
public List<string> week7List = new List<string>();
public List<string> week8List = new List<string>();
public List<string> week9List = new List<string>();
public List<string> week10List = new List<string>();
public DebateSchedulerForm(int x)
{
InitializeComponent();
initNames();
initWin();
initLoss();
initDates();
initDebates();
initWeekLists();
ListNames();
ListWin();
ListLoss();
ListDates();
if (x == ADMIN || x == GUEST)
{
Name1.ReadOnly = true;
Name2.ReadOnly = true;
Name3.ReadOnly = true;
Name4.ReadOnly = true;
Name5.ReadOnly = true;
Name6.ReadOnly = true;
Name7.ReadOnly = true;
Name8.ReadOnly = true;
Name9.ReadOnly = true;
Name10.ReadOnly = true;
Win1.ReadOnly = true;
Win2.ReadOnly = true;
Win3.ReadOnly = true;
Win4.ReadOnly = true;
Win5.ReadOnly = true;
Win6.ReadOnly = true;
Win7.ReadOnly = true;
Win8.ReadOnly = true;
Win9.ReadOnly = true;
Win10.ReadOnly = true;
Loss1.ReadOnly = true;
Loss2.ReadOnly = true;
Loss3.ReadOnly = true;
Loss4.ReadOnly = true;
Loss5.ReadOnly = true;
Loss6.ReadOnly = true;
Loss7.ReadOnly = true;
Loss8.ReadOnly = true;
Loss9.ReadOnly = true;
Loss10.ReadOnly = true;
ChangeDates.Visible = false;
Save.Visible = false;
}
}
public void Shuffle()
{
Random gen = new Random();
int n = debateList.Count();
while (n > 1)
{
n--;
int k = gen.Next(n + 1);
string value = debateList[k];
debateList[k] = debateList[n];
debateList[n] = value;
}
}
public void ListNames()
{
this.Name1.Text = nameList[0];
this.Name2.Text = nameList[1];
this.Name3.Text = nameList[2];
this.Name4.Text = nameList[3];
this.Name5.Text = nameList[4];
this.Name6.Text = nameList[5];
this.Name7.Text = nameList[6];
this.Name8.Text = nameList[7];
this.Name9.Text = nameList[8];
this.Name10.Text = nameList[9];
}
public void ListWin()
{
this.Win1.Text = winList[0];
this.Win2.Text = winList[1];
this.Win3.Text = winList[2];
this.Win4.Text = winList[3];
this.Win5.Text = winList[4];
this.Win6.Text = winList[5];
this.Win7.Text = winList[6];
this.Win8.Text = winList[7];
this.Win9.Text = winList[8];
this.Win10.Text = winList[9];
}
public void ListLoss()
{
this.Loss1.Text = lossList[0];
this.Loss2.Text = lossList[1];
this.Loss3.Text = lossList[2];
this.Loss4.Text = lossList[3];
this.Loss5.Text = lossList[4];
this.Loss6.Text = lossList[5];
this.Loss7.Text = lossList[6];
this.Loss8.Text = lossList[7];
this.Loss9.Text = lossList[8];
this.Loss10.Text = lossList[9];
}
public void ListDates()
{
this.Date1.Text = dateList[0];
this.Date2.Text = dateList[1];
this.Date3.Text = dateList[2];
this.Date4.Text = dateList[3];
this.Date5.Text = dateList[4];
this.Date6.Text = dateList[5];
this.Date7.Text = dateList[6];
this.Date8.Text = dateList[7];
this.Date9.Text = dateList[8];
this.Date10.Text = dateList[9];
}
public void initNames()
{
StreamReader sr = new StreamReader("nameList.txt");
for (int i = 0; i < 10; i++)
{
string line = sr.ReadLine();
nameList.Add(line);
}
sr.Close();
}
public void initWin()
{
StreamReader sw = new StreamReader("Win.txt");
for (int i = 0; i < 10; i++)
{
string line = sw.ReadLine();
winList.Add(line);
}
sw.Close();
}
public void initLoss()
{
StreamReader sw = new StreamReader("Loss.txt");
for (int i = 0; i < 10; i++)
{
string line = sw.ReadLine();
lossList.Add(line);
}
sw.Close();
}
public void initDates()
{
StreamReader sw = new StreamReader("Dates.txt");
for (int i = 0; i < 10; i++)
{
string line = sw.ReadLine();
dateList.Add(line);
}
sw.Close();
}
public void initDebates()
{
StreamReader sw = new StreamReader("Debate.txt");
for (int i = 0; i < 45; i++)
{
string line = sw.ReadLine();
debateList.Add(line);
}
sw.Close();
}
public void initWeekLists()
{
week1List.Add(debateList[0]);
week1List.Add(debateList[1]);
week1List.Add(debateList[2]);
week1List.Add(debateList[3]);
week1List.Add(debateList[4]);
week2List.Add(debateList[5]);
week2List.Add(debateList[6]);
week2List.Add(debateList[7]);
week2List.Add(debateList[8]);
week2List.Add(debateList[9]);
week3List.Add(debateList[10]);
week3List.Add(debateList[11]);
week3List.Add(debateList[12]);
week3List.Add(debateList[13]);
week3List.Add(debateList[14]);
week4List.Add(debateList[15]);
week4List.Add(debateList[16]);
week4List.Add(debateList[17]);
week4List.Add(debateList[18]);
week4List.Add(debateList[19]);
week5List.Add(debateList[20]);
week5List.Add(debateList[21]);
week5List.Add(debateList[22]);
week5List.Add(debateList[23]);
week5List.Add(debateList[24]);
week6List.Add(debateList[25]);
week6List.Add(debateList[26]);
week6List.Add(debateList[27]);
week6List.Add(debateList[28]);
week7List.Add(debateList[29]);
week7List.Add(debateList[30]);
week7List.Add(debateList[31]);
week7List.Add(debateList[32]);
week8List.Add(debateList[33]);
week8List.Add(debateList[34]);
week8List.Add(debateList[35]);
week8List.Add(debateList[36]);
week9List.Add(debateList[37]);
week9List.Add(debateList[38]);
week9List.Add(debateList[39]);
week9List.Add(debateList[40]);
week10List.Add(debateList[41]);
week10List.Add(debateList[42]);
week10List.Add(debateList[43]);
week10List.Add(debateList[44]);
}
public void finNames()
{
StreamWriter sw = new StreamWriter("nameList.txt");
sw.WriteLine(this.Name1.Text);
sw.WriteLine(this.Name2.Text);
sw.WriteLine(this.Name3.Text);
sw.WriteLine(this.Name4.Text);
sw.WriteLine(this.Name5.Text);
sw.WriteLine(this.Name6.Text);
sw.WriteLine(this.Name7.Text);
sw.WriteLine(this.Name8.Text);
sw.WriteLine(this.Name9.Text);
sw.WriteLine(this.Name10.Text);
sw.Close();
}
public void finWin()
{
StreamWriter sw = new StreamWriter("Win.txt");
sw.WriteLine(this.Win1.Text);
sw.WriteLine(this.Win2.Text);
sw.WriteLine(this.Win3.Text);
sw.WriteLine(this.Win4.Text);
sw.WriteLine(this.Win5.Text);
sw.WriteLine(this.Win6.Text);
sw.WriteLine(this.Win7.Text);
sw.WriteLine(this.Win8.Text);
sw.WriteLine(this.Win9.Text);
sw.WriteLine(this.Win10.Text);
sw.Close();
}
public void finLoss()
{
StreamWriter sw = new StreamWriter("Loss.txt");
sw.WriteLine(this.Loss1.Text);
sw.WriteLine(this.Loss2.Text);
sw.WriteLine(this.Loss3.Text);
sw.WriteLine(this.Loss4.Text);
sw.WriteLine(this.Loss5.Text);
sw.WriteLine(this.Loss6.Text);
sw.WriteLine(this.Loss7.Text);
sw.WriteLine(this.Loss8.Text);
sw.WriteLine(this.Loss9.Text);
sw.WriteLine(this.Loss10.Text);
sw.Close();
}
public void finDebates()
{
StreamWriter sw = new StreamWriter("Debate.txt");
for (int i = 0; i < 45; i++)
{
sw.WriteLine(debateList[i]);
}
sw.Close();
}
private void Save_Click(object sender, EventArgs e)
{
finNames();
finWin();
finLoss();
finDebates();
}
private void Close_Click(object sender, EventArgs e)
{
this.Close();
}
private void ChangeDates_Click(object sender, EventArgs e)
{
ChangeDates form = new ChangeDates(dateList);
form.ShowDialog();
initDates();
ListDates();
}
private void Date1_Click(object sender, EventArgs e)
{
Week_1 form = new Week_1(nameList, week1List);
form.ShowDialog();
}
private void Date2_Click(object sender, EventArgs e)
{
Week_2 form = new Week_2(nameList, week2List);
form.ShowDialog();
}
}
}

Assuming the debateList is the list you'd like to filter:
public List<string> debateList = new List<string>();
You can use Linq's GroupBy method chained with the SelectMany method and take advantage of the Take method which will take up to the max specified even if less are present:
List<string> result = debateList.GroupBy( x => x )
.SelectMany( x => x.Take( 2 ) )
.OrderBy( x => x )
.ToList()

You could set a counting variable, loop through the container and increment the counter each time an element is present in the container.