2021-07-09 ONNX from C#

This example shows how to compute the predictions of a model using C#.

using System.Collections.Generic;
using Microsoft.ML.OnnxRuntime;
using Microsoft.ML.OnnxRuntime.Tensors;

namespace ConsoleAppOnnx
{
    class Program
    {
        static void Main(string[] args)
        {
            // Loads the model.
            var opts = new SessionOptions();
            string model_path = "model.onnx";
            var session = new InferenceSession(model_path, opts);

            // Creating an input tensor (assuming there is only one).
            // Get the name of the input and the number of features.
            string name = string.Empty;
            int n_features = -1;
            foreach (var inp in session.InputMetadata)
            {
                name = inp.Key;
                n_features = inp.Value.Dimensions[1];
                break;
            }

            // Creates an empty input.
            var dims = new int[] { 1, n_features };
            var t = new DenseTensor<float>(dims);
            for (int i = 0; i < dims[1]; ++i)
                t.SetValue(i, 1.0f / (dims[1] + 1));
            var tensor = NamedOnnxValue.CreateFromTensor(name, t);

            // Runs the inference.
            var inputs = new List<NamedOnnxValue>() { tensor };
            using (var outputs = session.Run(inputs))
            {
                foreach (var o in outputs)
                {
                    DenseTensor<float> to = o.AsTensor<float>().ToDenseTensor();
                    var values = new float[to.Length];
                    to.Buffer.CopyTo(values);
                    // values contains the results.
                    foreach (var i in values)
                        System.Console.Write(string.Format("{0}, ", i));
                    System.Console.WriteLine();
                }
            }
        }
    }
}