VectorType attribute with dynamic dimension

The VectorType attribute can be added to an array-valued field when the length of the array is known at compile time, e.g.,

        public class Data
        {
            [ColumnName("Features")]
            [VectorType(2)]
            public float[] Features;

            [ColumnName("Label")]
            public bool Label;
        }

However, what if the length of the array is only known at run time?

For example, given IEnumerable<Data> data where the length of the Features array is given by int numFeatures, I need to be able to pass numFeatures to CollectionDataSource.Create(data) somehow, and remove the static 2 argument to the VectorType attribute on the Features field.

[drake7707]

@Anaschouihdi

Create a schema definition and pass it as the 2nd parameter in the LoadFromEnumerable method:

var schemaDef = SchemaDefinition.Create(typeof(Data));
schemaDef["Features"].ColumnType = new VectorDataViewType(NumberDataViewType.Single, 5);
var trainingDataView = mlContext.Data.LoadFromEnumerable(dataArray, schemaDef);

[drake7707]

One thing I forgot to mention is that you’ll also need to pass the same schema definition as an additional parameter inputSchemaDefinition in the prediction engine:

var predEngine = mlContext.Model.CreatePredictionEngine<IrisData, IrisPrediction>(trainedModel, inputSchemaDefinition: schemaDef);