asked on

C# Program List Iteration

Experts,

I`m using VS 2008 C# 3.5 Maybe this question belongs in the Algorithm section.

Please look at the code below, and I think this is overkill - the number of iterations is way too much and costing performance. A more efficient algorithm would be greatly appreciated.

namespace WindowsFormsApplication9
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //This is a very simple example of what I`m trying to do. For the sake of simplicity I`ve take a Car info example.

            //This is just list of Class DumClass. Which contains ID, EnumValue (Name, Year and Model) and StrValue
            List<DumClass> DumList = new List<DumClass>();

            DumList.Add(new DumClass(00, EnumType.Model, "Audi"));
            DumList.Add(new DumClass(00, EnumType.Name, "A6"));
            DumList.Add(new DumClass(01, EnumType.Model, "Toyota"));
            DumList.Add(new DumClass(01, EnumType.Year, "1998"));
            DumList.Add(new DumClass(10, EnumType.Name, "Honda"));
            DumList.Add(new DumClass(10, EnumType.Year, "2004"));
            DumList.Add(new DumClass(10, EnumType.Name, "Civic"));

            //I want to display the information in this format.
            //Notice for every ID, some information might be absent.

            //Function here - Display
            //ID   Name   Year   Model
            //00   A6            Audi
            //01          1998   Toyota
            //10   Honda  2004   Civic


            //I create a list of IDs.
            List<int> IDList = new List<int>();

            for (int i = 0; i < DumList.Count; i++)
            {
                IDList.Add(DumList[i].ID);
            }

            //Sort the IDs and make it unique.
            IDList.Sort();
            IDList = IDList.Distinct().ToList();

            //Loop through the IDs through the Dumlist and see if the information is present. 
            //If present write it. 

            //Lets say, I have a IDList has a few 1000 unique entries and then the DumList has another 50000 entries.
            //Thats 1000 * 50000 iterations!! 
            //There should be a better way of doing this.
            for (int i = 0; i < IDList.Count; i++)
            {
                int ID = IDList[i];

                Console.Write(ID + "\t");
            
                for (int j = 0; j < DumList.Count; j++)
                {
                    DumClass DObj = DumList[j];

                    if (ID == DObj.ID)
                    {
                        if (DObj.EnumVal == EnumType.Name)
                        {
                            Console.Write(DObj.StrValue + "\t");
                        }
                        else
                        {
                            Console.Write("\t");
                        }

                        if (DObj.EnumVal == EnumType.Year)
                        {
                            Console.Write(DObj.StrValue + "\t");
                        }
                        else
                        {
                            Console.Write("\t");
                        }

                        if (DObj.EnumVal == EnumType.Model)
                        {
                            Console.Write(DObj.StrValue + "\t");
                        }
                        else
                        {
                            Console.Write("\t");
                        }
                    }
                }

                Console.WriteLine();
            }

        }
    }

    public enum EnumType {Name, Year, Model};

    public class DumClass
    {
        public int ID;
        public EnumType EnumVal;
        public string StrValue;
        
        public DumClass(int id, EnumType enumVal, string strVal)
        {
            ID = id;
            EnumVal = enumVal;
            StrValue = strVal;
        }
    }
}

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San24

ASKER

Separated by commas makes more sense. That way I can open it as a CSV file.

//ID , Name, Year, Model
//00, A6, , Audi
//01, , 1998, Toyota
//10 , Honda, 2004, Civic

ASKER CERTIFIED SOLUTION

wdosanjos

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wdosanjos

For comma delimited, just update the foreach as follows:

Console.WriteLine("ID,Name,Year,Model");  // Header

foreach (var car in query)
{
    Console.WriteLine("{0},{1},{2},{3}", car.ID, car.Name, car.Year, car.Model);  // Row
}

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SOLUTION

Mike Tomlinson

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San24

ASKER

wdosanjos - Thats just an amazing peice of code! Very cool.
Idle_Mind - You "not as elegant" code is way better than what I started off. Thanks.

Let me implement this method in my code, which is more complex. Also, I`ll update you guys on execution time taken difference. I`m guessing it`ll be phenomenol. Once I have everything running I`ll assign the points. Thanks a lot guys!

San24

ASKER

Year = g.Max(c => (c.EnumVal == EnumType.Year) ? c.StrValue : "")

If I want Year to be a double, and I want a "null" value instead of "" How woul;d I go about that?

Year = g.Max(c => (c.EnumVal == EnumType.Year) ? c.Value : null) //This throws an error.

wdosanjos

In that case you would need something like this:

Year = g.Max(c => (c.EnumVal == EnumType.Year) ? double.Parse(c.StrValue) : (double?)null)

San24

ASKER

wdosanjos - Thanks Again. I just implemented everything and the execution time for my data set reduced by 58%. Thats crazy.

I will look into using LINQ more.