## Jagged shared variable arrays

To define a jagged shared variable array, it is useful first of all to create aliases for the jagged distribution array types that define your jagged random variable array. For example:

``````using GaussianArray=DistributionStructArray<Gaussian, double>;
using GaussianArrayArray=DistributionRefArray<DistributionStructArray<Gaussian, double>, double[]>
``````

or

``````using DirichletArray=DistributionRefArray<Dirichlet, Vector>;
using DirichletArrayArray=DistributionRefArray<DistributionRefArray<Dirichlet, Vector>, Vector[]>;
``````

Below is an example where we want to learn the mean of jagged array of Gaussian-distributed data using shared variables. The line defining the jagged shared variable array is highlighted:

``````double[][][] data = new double[][][] {
new double[][] { new double[] { 1,2 }, new double[] { 3,4 } },
new double[][] { new double[] { 5,6 }, new double[] { 7,8 } }
};
int numChunks = data.Length;
Range outer = new Range(data.Length);
Range inner = new Range(data.Length);
GaussianArrayArray priorW =
new GaussianArrayArray(new GaussianArray(new Gaussian(0, 1), inner.SizeAsInt), outer.SizeAsInt);

var w = SharedVariable<double>.Random(Variable.Array<double>(inner), outer, priorW).Named("w");
Model model = new Model(numChunks);
var x = Variable.Array<double>(Variable.Array<double>(inner), outer).Named("x");
x[outer][inner] = Variable.GaussianFromMeanAndPrecision(w.GetCopyFor(model)[outer][inner], 1.0);
InferenceEngine engine = new InferenceEngine();

for (int pass = 0; pass < 5; pass++)
{
for (int c = 0; c < numChunks; c++)
{
x.ObservedValue = data[c];
model.InferShared(engine, c);
}
}
var posteriorW = w.Marginal<Gaussian[][]>();
``````

If you want to make a jagged array with more than 2 brackets, you will need to specify the full array type as the type argument to SharedVariable. (This also works with 2 brackets, but isn’t needed.) For example, to make an array with 3 brackets:

``````var x = SharedVariable<double[][][]>.Random(Variable.Array(Variable.Array<double>(innerinner), inner), outer, prior);
``````