CODEWITHSUNDEEP
c#listdata-structures
Pankaj
Pankaj

Reputation: 2744

Data Type of holding multiple Data

I want an datatype which can hold an Integer and Char.

private Int32[] XCordinates = {0,1,2,3,4,5,6,7,8,9 };
private Char[] yCordinates = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J' };

and I want result something like this

A0
A1
A2
A3
A4 and so on.... upto 
J8
J9

Now which data type should I use for the fastest performance and data retrieval from lets Say "H6" entry.

  1. Dictionaries are out of equation since they don't allow multiple keys

  2. ArrayList could be used but it can store only one type of object and required boxing/unboxing.

or I can use 

List<KeyValuePair<Char, Int32>> myKVPList = new List<KeyValuePair<Char, Int32>>();
foreach (Char yValue in yCordinates)
{
   foreach (Int32 xValue in XCordinates)
   {
       myKVPList.Add(new KeyValuePair<Char, Int32>(yValue, xValue));
    }
 }

but List are slowest in accessing data as compared to arrays, Any suggestions ?

Upvotes: 0

Views: 259

Answers (2)

terrybozzio
terrybozzio

Reputation: 4542

you can try the byte representation of characters and numbers then formatt them:

        //values from 48-57 are 0 to 9,65-90 uppercase letters,97-122 lowercase letters
        byte[] ba = new byte[] { 65, 49, 70, 52, 88, 55 };

        for (int i = 0; i < ba.Length; i += 2)
        {
            Console.WriteLine(string.Format("{0}{1}",(char)ba[i],(char)ba[i + 1]));
        }

        Console.ReadKey();

If you really dont want to use dictionary you can also try just string representation:

            string[] vals = new string[] { "A122", "C67", "T8" };
            foreach (var item in vals)
            {
                //this is just to show you can convert to an int because if its
                //one letter and numbers you know index 1 of string will be
                //the start of the number representation.
                int count = int.Parse(item.Substring(1, item.Length - 1));
                Console.WriteLine("{0},{1}", item.Substring(0, 1), item.Substring(1, item.Length - 1));
            }

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460028

The .NET framework 3.5 includes a special LINQ Lookup class.

var lookup = (from x in yCordinates
             from y in XCordinates
             select new{x, y}).ToLookup(xy => xy.x, xy => xy.y);

foreach(var xy in lookup)
    Console.WriteLine("x:{0} y-values:{1}", xy.Key, string.Join(",", xy.Select(y => y)));

Result:

x:A y-values:0,1,2,3,4,5,6,7,8,9
x:B y-values:0,1,2,3,4,5,6,7,8,9
x:C y-values:0,1,2,3,4,5,6,7,8,9
x:D y-values:0,1,2,3,4,5,6,7,8,9
x:E y-values:0,1,2,3,4,5,6,7,8,9
x:F y-values:0,1,2,3,4,5,6,7,8,9
x:G y-values:0,1,2,3,4,5,6,7,8,9
x:H y-values:0,1,2,3,4,5,6,7,8,9
x:I y-values:0,1,2,3,4,5,6,7,8,9
x:J y-values:0,1,2,3,4,5,6,7,8,9

A Lookup<TKey, TElement> is similar to a Dictionary<TKey, TValue>. The difference is that a Dictionary<TKey, TValue> maps keys to single values, whereas a Lookup<TKey, TElement> maps keys to collections of values.

It's drawbacks are:

  • you cant just create a Lookup object since there is no public constructor, its only available using the .ToLookup method
  • you cannot edit it once it has been created, no Add or Remove etc.

As a side note, you can query a lookup (via the indexer) on a key that doesn't exist, and you'll get an empty sequence. Do the same with a dictionary and you'll get an exception.

Upvotes: 1

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