Changes to onnx export. (dotnet#5544)

Author: michaelgsharp

Microsoft.ML.sln

@@ -49,18 +49,12 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Maml", "src\Mi
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Console", "src\Microsoft.ML.Console\Microsoft.ML.Console.csproj", "{362A98CF-FBF7-4EBB-A11B-990BBF845B15}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "build", "build", "{487213C9-E8A9-4F94-85D7-28A05DBBFE3A}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "netstandard2.0", "netstandard2.0", "{9252A8EB-ABFB-440C-AB4D-1D562753CE0F}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Sweeper.Tests", "test\Microsoft.ML.Sweeper.Tests\Microsoft.ML.Sweeper.Tests.csproj", "{3DEB504D-7A07-48CE-91A2-8047461CB3D4}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.LightGbm", "src\Microsoft.ML.LightGbm\Microsoft.ML.LightGbm.csproj", "{001F3B4E-FBE4-4001-AFD2-A6A989CD1C25}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Ensemble", "src\Microsoft.ML.Ensemble\Microsoft.ML.Ensemble.csproj", "{DCF46B79-1FDB-4DBA-A263-D3D64E3AAA27}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.CpuMath", "Microsoft.ML.CpuMath", "{BF66A305-DF10-47E4-8D81-42049B149D2B}"
-EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tools-local", "tools-local", "{7F13E156-3EBA-4021-84A5-CD56BA72F99E}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.InternalCodeAnalyzer", "tools-local\Microsoft.ML.InternalCodeAnalyzer\Microsoft.ML.InternalCodeAnalyzer.csproj", "{B4E55B2D-2A92-46E7-B72F-E76D6FD83440}"
@@ -109,76 +103,32 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.DnnImageFeatur
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.EntryPoints", "src\Microsoft.ML.EntryPoints\Microsoft.ML.EntryPoints.csproj", "{7504D46F-E4B3-43CB-9B1C-82F3131F1C99}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.Mkl.Components", "Microsoft.ML.Mkl.Components", "{63006A14-B924-48C5-83C9-CFE9DA22B01F}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.ImageAnalytics", "Microsoft.ML.ImageAnalytics", "{1229F799-37F0-4282-B9F0-74BFA97CC362}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.LightGbm", "Microsoft.ML.LightGbm", "{DE95FE65-9FF7-4233-93DF-7A8F2805624A}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.Mkl.Redist", "Microsoft.ML.Mkl.Redist", "{4CF8095E-B4A3-4326-A550-43098E447288}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.OnnxConverter", "Microsoft.ML.OnnxConverter", "{19AC192B-75FE-45D5-B219-898E401D5904}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.OnnxTransformer", "Microsoft.ML.OnnxTransformer", "{93FF16AA-635E-421D-96C1-008818C143A2}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.Recommender", "Microsoft.ML.Recommender", "{320AF46A-4809-486E-8F9E-A00C8AE47751}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.TensorFlow", "Microsoft.ML.TensorFlow", "{11894B4A-78B4-4523-A6DD-4495722E244F}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.TimeSeries", "Microsoft.ML.TimeSeries", "{B836F712-7FB6-4B75-A3EB-FB05F8E0D15E}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.DnnImageFeaturizer.AlexNet", "Microsoft.ML.DnnImageFeaturizer.AlexNet", "{B00098E4-771E-41DF-A3AA-A606AAB334B7}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.DnnImageFeaturizer.ResNet18", "Microsoft.ML.DnnImageFeaturizer.ResNet18", "{BD93C0F3-3CED-4BE8-9389-4234250FBFB1}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.DnnImageFeaturizer.ResNet50", "Microsoft.ML.DnnImageFeaturizer.ResNet50", "{8EDFB7E5-7E7E-411D-99C5-7A4895D0F9CB}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.DnnImageFeaturizer.ResNet101", "Microsoft.ML.DnnImageFeaturizer.ResNet101", "{9E689AD4-F908-493C-B882-B1B33E8F7696}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.EntryPoints", "Microsoft.ML.EntryPoints", "{8D8CC016-0020-40EC-BD8E-73F1CE0F9662}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "common", "common", "{A84717CB-F11A-41C5-A74D-C0F1D47B7431}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.DataView", "src\Microsoft.ML.DataView\Microsoft.ML.DataView.csproj", "{85D0CAFD-2FE8-496A-88C7-585D35B94243}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.DataView", "Microsoft.ML.DataView", "{31D38B21-102B-41C0-9E0A-2FE0BF68D123}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "RemoteExecutorConsoleApp", "test\RemoteExecutorConsoleApp\RemoteExecutorConsoleApp.csproj", "{5E920CAC-5A28-42FB-936E-49C472130953}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.Ensemble", "Microsoft.ML.Ensemble", "{AD7058C9-5608-49A8-BE23-58C33A74EE91}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Experimental", "src\Microsoft.ML.Experimental\Microsoft.ML.Experimental.csproj", "{E02DA82D-3FEE-4C60-BD80-9EC3C3448DFC}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.FastTree", "Microsoft.ML.FastTree", "{B1B3F284-FA3D-4D76-A712-FF04495D244B}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.Extensions.ML", "src\Microsoft.Extensions.ML\Microsoft.Extensions.ML.csproj", "{D6741C37-B5E6-4050-BCBA-9715809EA15B}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.Extensions.ML.Tests", "test\Microsoft.Extensions.ML.Tests\Microsoft.Extensions.ML.Tests.csproj", "{21CAD3A1-5E1F-42C1-BB73-46B6E67F4206}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.Extensions.ML", "Microsoft.Extensions.ML", "{AE4F7569-26F3-4160-8A8B-7A57D0DA3350}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.StableApi", "tools-local\Microsoft.ML.StableApi\Microsoft.ML.StableApi.csproj", "{F308DC6B-7E59-40D7-A581-834E8CD99CFE}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.AutoML.Tests", "test\Microsoft.ML.AutoML.Tests\Microsoft.ML.AutoML.Tests.csproj", "{C2652287-CD6D-40FB-B042-95FB56D09DB8}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.AutoML", "src\Microsoft.ML.AutoML\Microsoft.ML.AutoML.csproj", "{E48285BF-F49A-4EA3-AED0-1BDDBF77EB80}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.AutoML", "Microsoft.ML.AutoML", "{F5D11F71-2D61-4AE9-99D7-0F0B54649B15}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.AutoML.Samples", "docs\samples\Microsoft.ML.AutoML.Samples\Microsoft.ML.AutoML.Samples.csproj", "{A6924919-9E37-4023-8B7F-E85C8E3CC9B3}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Samples.GPU", "docs\samples\Microsoft.ML.Samples.GPU\Microsoft.ML.Samples.GPU.csproj", "{3C8F910B-7F23-4D25-B521-6D5AC9570ADD}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Featurizers", "src\Microsoft.ML.Featurizers\Microsoft.ML.Featurizers.csproj", "{E2DD0721-5B0F-4606-8182-4C7EFB834518}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.Featurizers", "Microsoft.ML.Featurizers", "{1BA5C784-52E8-4A87-8525-26B2452F2882}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.CodeGenerator", "src\Microsoft.ML.CodeGenerator\Microsoft.ML.CodeGenerator.csproj", "{56CB0850-7341-4D71-9AE4-9EFC472D93DD}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.CodeGenerator.Tests", "test\Microsoft.ML.CodeGenerator.Tests\Microsoft.ML.CodeGenerator.Tests.csproj", "{46CC5637-3DDF-4100-93FC-44BB87B2DB81}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Microsoft.ML.CodeGenerator", "Microsoft.ML.CodeGenerator", "{3817A875-278C-4140-BF66-3C4A8CA55F0D}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Vision", "src\Microsoft.ML.Vision\Microsoft.ML.Vision.csproj", "{419F93D5-4135-4DA0-A76E-EFC23E04093D}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.TestFrameworkCommon", "test\Microsoft.ML.TestFrameworkCommon\Microsoft.ML.TestFrameworkCommon.csproj", "{A22FAD27-77E8-4460-8B92-EC7090B7173A}"
@@ -187,10 +137,6 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.NightlyBuild.T
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.NugetPackageVersionUpdater", "test\Microsoft.ML.NugetPackageVersionUpdater\Microsoft.ML.NugetPackageVersionUpdater.csproj", "{C8DB58DC-6434-4431-A81F-263D86E2A5F3}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "build", "build", "{C91F81E3-B900-4968-A6DF-F53B515E97E1}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "netstandard2.0", "netstandard2.0", "{027DBA48-85B6-46F1-9487-0B49B5057FC0}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML", "src\Microsoft.ML\Microsoft.ML.csproj", "{6CF88209-69DB-4B36-9604-3ECD9F163E96}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.ML.Mkl.Redist", "src\Microsoft.ML.Mkl.Redist\Microsoft.ML.Mkl.Redist.csproj", "{4584326B-C5B3-4CAE-B98A-34C5F5AA16F3}"
@@ -1759,7 +1705,6 @@ Global
 {7A9DB75F-2CA5-4184-9EF5-1F17EB39483F} = {AED9C836-31E3-4F3F-8ABC-929555D3F3C4}
 {64F40A0D-D4C2-4AA7-8470-E9CC437827E4} = {09EADF06-BE25-4228-AB53-95AE3E15B530}
 {362A98CF-FBF7-4EBB-A11B-990BBF845B15} = {09EADF06-BE25-4228-AB53-95AE3E15B530}
-{9252A8EB-ABFB-440C-AB4D-1D562753CE0F} = {487213C9-E8A9-4F94-85D7-28A05DBBFE3A}
 {3DEB504D-7A07-48CE-91A2-8047461CB3D4} = {AED9C836-31E3-4F3F-8ABC-929555D3F3C4}
 {001F3B4E-FBE4-4001-AFD2-A6A989CD1C25} = {09EADF06-BE25-4228-AB53-95AE3E15B530}
 {DCF46B79-1FDB-4DBA-A263-D3D64E3AAA27} = {09EADF06-BE25-4228-AB53-95AE3E15B530}
@@ -1802,8 +1747,6 @@ Global
 {A22FAD27-77E8-4460-8B92-EC7090B7173A} = {AED9C836-31E3-4F3F-8ABC-929555D3F3C4}
 {A1CAC86F-F4BB-4B6D-9D18-E9AE15B3C66E} = {AED9C836-31E3-4F3F-8ABC-929555D3F3C4}
 {C8DB58DC-6434-4431-A81F-263D86E2A5F3} = {AED9C836-31E3-4F3F-8ABC-929555D3F3C4}
-{C91F81E3-B900-4968-A6DF-F53B515E97E1} = {BF66A305-DF10-47E4-8D81-42049B149D2B}
-{027DBA48-85B6-46F1-9487-0B49B5057FC0} = {C91F81E3-B900-4968-A6DF-F53B515E97E1}
 {6CF88209-69DB-4B36-9604-3ECD9F163E96} = {09EADF06-BE25-4228-AB53-95AE3E15B530}
 {4584326B-C5B3-4CAE-B98A-34C5F5AA16F3} = {09EADF06-BE25-4228-AB53-95AE3E15B530}
 EndGlobalSection

src/Microsoft.ML.OnnxConverter/OnnxExportExtensions.cs

@@ -4,6 +4,7 @@
 
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using Google.Protobuf;
 using Microsoft.ML.Data;
 using Microsoft.ML.Model.OnnxConverter;
@@ -14,30 +15,43 @@ namespace Microsoft.ML
 {
  public static class OnnxExportExtensions
  {
- private static ModelProto ConvertToOnnxProtobufCore(IHostEnvironment env, OnnxContextImpl ctx, ITransformer transform, IDataView inputData)
+ private static ModelProto ConvertToOnnxProtobufCore(IHostEnvironment env, OnnxContextImpl ctx, ITransformer transform, IDataView inputData, string[] outputColumnNamesToKeep = null)
  {
  var outputData = transform.Transform(inputData);
  LinkedList<ITransformCanSaveOnnx> transforms = null;
  using (var ch = env.Start("ONNX conversion"))
  {
  SaveOnnxCommand.GetPipe(ctx, ch, outputData, out IDataView root, out IDataView sink, out transforms);
- return SaveOnnxCommand.ConvertTransformListToOnnxModel(ctx, ch, root, sink, transforms, null, null);
+ // We pass in the output names to keep, but this next call expects a list of ones to drop. Invert the list.
+ var outputColumnNamesToDrop = new HashSet<string>();
+ if (outputColumnNamesToKeep != null)
+ {
+ for (int i = 0; i < sink.Schema.Count; ++i)
+ {
+ if (!outputColumnNamesToKeep.Contains(sink.Schema[i].Name))
+ {
+ outputColumnNamesToDrop.Add(sink.Schema[i].Name);
+ }
+ }
+ }
+ return SaveOnnxCommand.ConvertTransformListToOnnxModel(ctx, ch, root, sink, transforms, null, outputColumnNamesToDrop);
  }
  }
 
  /// <summary>
  /// Convert the specified <see cref="ITransformer"/> to ONNX format. Note that ONNX uses Google's Protobuf so the returned value is a Protobuf object.
  /// </summary>
- /// <param name="catalog">The class that <see cref="ConvertToOnnxProtobuf(ModelOperationsCatalog, ITransformer, IDataView)"/> attached to.</param>
+ /// <param name="catalog">The class that <see cref="ConvertToOnnxProtobuf(ModelOperationsCatalog, ITransformer, IDataView, string[])"/> attached to.</param>
  /// <param name="transform">The <see cref="ITransformer"/> that will be converted into ONNX format.</param>
  /// <param name="inputData">The input of the specified transform.</param>
+ /// <param name="outputColumns">List of output columns we want to keep.</param>
  /// <returns>An ONNX model equivalent to the converted ML.NET model.</returns>
  [BestFriend]
- internal static ModelProto ConvertToOnnxProtobuf(this ModelOperationsCatalog catalog, ITransformer transform, IDataView inputData)
+ internal static ModelProto ConvertToOnnxProtobuf(this ModelOperationsCatalog catalog, ITransformer transform, IDataView inputData, string[] outputColumns=null)
  {
  var env = catalog.GetEnvironment();
  var ctx = new OnnxContextImpl(env, "model", "ML.NET", "0", 0, "machinelearning.dotnet", OnnxVersion.Stable);
- return ConvertToOnnxProtobufCore(env, ctx, transform, inputData);
+ return ConvertToOnnxProtobufCore(env, ctx, transform, inputData, outputColumns);
  }
 
  /// <summary>
@@ -78,5 +92,17 @@ public static void ConvertToOnnx(this ModelOperationsCatalog catalog, ITransform
  /// <returns>An ONNX model equivalent to the converted ML.NET model.</returns>
  public static void ConvertToOnnx(this ModelOperationsCatalog catalog, ITransformer transform, IDataView inputData, int opSetVersion, Stream stream) =>
  ConvertToOnnxProtobuf(catalog, transform, inputData, opSetVersion).WriteTo(stream);
+
+ /// <summary>
+ /// Convert the specified <see cref="ITransformer"/> to ONNX format and writes to a stream.
+ /// </summary>
+ /// <param name="catalog">The class that <see cref="ConvertToOnnx(ModelOperationsCatalog, ITransformer, IDataView, Stream)"/> attached to.</param>
+ /// <param name="transform">The <see cref="ITransformer"/> that will be converted into ONNX format.</param>
+ /// <param name="inputData">The input of the specified transform.</param>
+ /// <param name="stream">The stream to write the protobuf model to.</param>
+ /// <param name="outputColumns">List of output columns we want to keep.</param>
+ /// <returns>An ONNX model equivalent to the converted ML.NET model.</returns>
+ public static void ConvertToOnnx(this ModelOperationsCatalog catalog, ITransformer transform, IDataView inputData, Stream stream, params string[] outputColumns) =>
+ ConvertToOnnxProtobuf(catalog, transform, inputData, outputColumns).WriteTo(stream);
  }
 }

src/Microsoft.ML.OnnxTransformer/OnnxTransform.cs

@@ -553,7 +553,7 @@ public void Dispose()
  }
  }
 
- private void UpdateCacheIfNeeded(long position, INamedOnnxValueGetter[] srcNamedOnnxValueGetters, string[] activeOutputColNames, OnnxRuntimeOutputCacher outputCache)
+ private void UpdateCacheIfNeeded(long position, INamedOnnxValueGetter[] srcNamedOnnxValueGetters, List<string> activeOutputColNames, OnnxRuntimeOutputCacher outputCache)
  {
  if (outputCache.Position != position)
  {
@@ -565,7 +565,7 @@ private void UpdateCacheIfNeeded(long position, INamedOnnxValueGetter[] srcNamed
  }
 
  outputCache.OutputOnnxValues?.Dispose();
- outputCache.OutputOnnxValues = _parent.Model.Run(inputNameOnnxValues);
+ outputCache.OutputOnnxValues = _parent.Model.Run(inputNameOnnxValues, activeOutputColNames);
  Contracts.Assert(outputCache.OutputOnnxValues.Count > 0);
 
  foreach (var outputNameOnnxValue in outputCache.OutputOnnxValues)
@@ -580,9 +580,10 @@ private Delegate MakeTensorGetter<T>(DataViewRow input, int iinfo, INamedOnnxVal
  string[] activeOutputColNames, OnnxRuntimeOutputCacher outputCacher)
  {
  Host.AssertValue(input);
+ var listActiveOutputColumns = activeOutputColNames.ToList();
  ValueGetter<VBuffer<T>> valueGetter = (ref VBuffer<T> dst) =>
  {
- UpdateCacheIfNeeded(input.Position, srcNamedValueGetters, activeOutputColNames, outputCacher);
+ UpdateCacheIfNeeded(input.Position, srcNamedValueGetters, listActiveOutputColumns, outputCacher);
  var namedOnnxValue = outputCacher.Outputs[_parent.Outputs[iinfo]];
  var tensor = namedOnnxValue.AsTensor<T>() as Microsoft.ML.OnnxRuntime.Tensors.DenseTensor<T>;
  if (tensor == null)
@@ -598,10 +599,11 @@ private Delegate MakeStringTensorGetter(DataViewRow input, int iinfo, INamedOnnx
  string[] activeOutputColNames, OnnxRuntimeOutputCacher outputCacher)
  {
  Host.AssertValue(input);
+ var listActiveOutputColumns = activeOutputColNames.ToList();
 
  ValueGetter<VBuffer<ReadOnlyMemory<char>>> valueGetter = (ref VBuffer<ReadOnlyMemory<char>> dst) =>
  {
- UpdateCacheIfNeeded(input.Position, srcNamedValueGetters, activeOutputColNames, outputCacher);
+ UpdateCacheIfNeeded(input.Position, srcNamedValueGetters, listActiveOutputColumns, outputCacher);
  var namedOnnxValue = outputCacher.Outputs[_parent.Outputs[iinfo]];
  var tensor = namedOnnxValue.AsTensor<string>() as Microsoft.ML.OnnxRuntime.Tensors.DenseTensor<string>;
  if (tensor == null)
@@ -621,10 +623,11 @@ private Delegate MakeObjectGetter<T>(DataViewRow input, int iinfo, INamedOnnxVal
  string[] activeOutputColNames, OnnxRuntimeOutputCacher outputCacher)
  {
  Host.AssertValue(input);
+ var listActiveOutputColumns = activeOutputColNames.ToList();
 
  ValueGetter<T> valueGetter = (ref T dst) =>
  {
- UpdateCacheIfNeeded(input.Position, srcNamedValueGetters, activeOutputColNames, outputCacher);
+ UpdateCacheIfNeeded(input.Position, srcNamedValueGetters, listActiveOutputColumns, outputCacher);
  var namedOnnxValue = outputCacher.Outputs[_parent.Outputs[iinfo]];
  var trueValue = namedOnnxValue.AsEnumerable<NamedOnnxValue>().Select(value => value.AsDictionary<string, float>());
  var caster = _parent.Model.ModelInfo.OutputsInfo[_parent.MapDataViewColumnToOnnxOutputTensor(iinfo)].Caster;