ML.NET export to ONNX - onnx

Question

NET GUI tools to train model. The model works great with C# application, but I want to have it in ONNX format. I have found tools which are converting between model formats, but couldn't find anything for ML.NET generated format. Apparently it's some zip file, and nothing more I know about it. does anyone know a tool to do conversion to ONNX.
Thanks
Microsoft's ML.Net Model Builder generates code
// Load Data
IDataView trainingDataView = mlContext.Data.LoadFromTextFile<ModelInput>(
path: TRAIN_DATA_FILEPATH,
hasHeader: true,
separatorChar: ',',
allowQuoting: true,
allowSparse: false);
// Build training pipeline
IEstimator<ITransformer> trainingPipeline = BuildTrainingPipeline(mlContext);
// Train Model
ITransformer mlModel = TrainModel(mlContext, trainingDataView, trainingPipeline);
// Evaluate quality of Model
Evaluate(mlContext, trainingDataView, trainingPipeline);
// Save model
SaveModel (mlContext, mlModel, MODEL_FILE, trainingDataView.Schema);
var path = GetAbsolutePath(MODEL_FILE);
path = new FileInfo(path).Directory.FullName;
path = Path.Combine(path, "mymodel.onnx");
using (var onnx = File.Open(path, FileMode.OpenOrCreate))
{
mlContext.Model.ConvertToOnnx(mlModel, trainingDataView, onnx);
}
from
var path = GetAbsolutePath(MODEL_FILE);
path = new FileInfo(path).Directory.FullName;
path = Path.Combine(path, "mymodel.onnx");
using (var onnx = File.Open(path, FileMode.OpenOrCreate))
{
mlContext.Model.ConvertToOnnx(mlModel, trainingDataView, onnx);
}
I have modified.
I am getting onnx file, but I am not able to run it(inference). Likewise, I have tried to open it with WinML Dashboard, but it's also not able to run generated onnx. I wonder perhaps it's the version of the onnx it generates?
the model is simple regression with all inputs float numbers and output one float as well.

Answer 1

Use the Microsoft.ML.OnnxConverter NuGet Package. Something like this:
var mlContext = new MLContext();
...
IDataView trainingData = mlContext.Data.LoadFromEnumerable(inputData);
var pipeline = mlContext.Transforms.Concatenate("Features", ... )
.Append(...));
var model = pipeline.Fit(trainingData);
using (var onnx = File.Open("mymodel.onnx", FileMode.OpenOrCreate))
{
mlContext.Model.ConvertToOnnx(model, trainingData, onnx);
}