**Previous instalments**

**General Data Structures**

**Trees**

Looking at tree structures will make your eyes bleed, so we’ll take a break to discuss one of the simpler data structures NGenerics offers - the ObjectMatrix. The ObjectMatrix is a representation of a 2-dimensional array of objects, like, for example, a game board :

Why not use a two-dimensional array in the first place? The ObjectMatrix offers the following useful operations at the time of writing:

**Rows**and**Columns**- formal definition of rows and columns - much better than having`.Length`

scattered all over your code.**GetSubMatrix**- enables the retrieval of a subset of the matrix.**InterchangeRows**and**InterchangeColumns**- swap individual rows and columns.**GetRow**and**GetColumn**- provides an easy way of retrieving individual rows and columns.**AddRow**and**AddColumn**- add new rows and columns when you need more space.**DeleteRow**and**DeleteColumn**- delete individual rows and columns.**Resize**- resize the matrix to have any arbitrary column/row count.

Use it like you would use any two dimensional array :

```
var matrix = new ObjectMatrix(3, 3);
matrix[0, 0] = new Cross();
matrix[0, 1] = new Nought();
matrix[0, 2] = new Nought();
matrix[1, 0] = new Nought();
matrix[1, 1] = new Cross();
matrix[2, 2] = new Cross();
var enumerator = matrix.GetEnumerator();
while (enumerator.MoveNext())
{
Console.WriteLine(enumerator.Current);
}
```

The ObjectMatrix is also the base class for one of the biggest classes in NGenerics - the mathematical Matrix, which we’ll get to in a later post.

**Photo by Markus Spiske on Unsplash**