Added onnx export support for WordTokenizingTransformer and NgramExtr…

…actingTransformer (#4451)

* Added onnx export support for string related transforms

* Updated baseline test files

A large portion of this commit is upgrading the baseline test files. The rest of the fixes deal with build breaks resulting from the upgrade of ORT version.

* Fixed bugs in ValueToKeyMappingTransformer and added additional tests

src/Microsoft.ML.Data/Transforms/KeyToVector.cs

@@ -606,16 +606,11 @@ public void SaveAsOnnx(OnnxContext ctx)
                     ColInfo info = _infos[iinfo];
                     string inputColumnName = info.InputColumnName;
                     if (!ctx.ContainsColumn(inputColumnName))
-                    {
-                        ctx.RemoveColumn(info.Name, false);
                         continue;
-                    }
 
-                    if (!SaveAsOnnxCore(ctx, iinfo, info, ctx.GetVariableName(inputColumnName),
-                        ctx.AddIntermediateVariable(_types[iinfo], info.Name)))
-                    {
-                        ctx.RemoveColumn(info.Name, true);
-                    }
+                    var srcVariableName = ctx.GetVariableName(inputColumnName);
+                    var dstVariableName = ctx.AddIntermediateVariable(_types[iinfo], info.Name);
+                    SaveAsOnnxCore(ctx, iinfo, info, srcVariableName, dstVariableName);
                 }
             }
 
@@ -692,7 +687,7 @@ private JToken SaveAsPfaCore(BoundPfaContext ctx, int iinfo, ColInfo info, JToke
                     PfaUtils.Call("cast.fanoutDouble", -1, 0, keyCount, false), PfaUtils.FuncRef("u." + funcName));
             }
 
-            private bool SaveAsOnnxCore(OnnxContext ctx, int iinfo, ColInfo info, string srcVariableName, string dstVariableName)
+            private void SaveAsOnnxCore(OnnxContext ctx, int iinfo, ColInfo info, string srcVariableName, string dstVariableName)
             {
                 var shape = ctx.RetrieveShapeOrNull(srcVariableName);
                 // Make sure that shape must present for calculating the reduction axes. The shape here is generally not null
@@ -703,8 +698,13 @@ private bool SaveAsOnnxCore(OnnxContext ctx, int iinfo, ColInfo info, string src
                 // default ONNX LabelEncoder just matches the behavior of Bag=false.
                 var encodedVariableName = _parent._columns[iinfo].OutputCountVector ? ctx.AddIntermediateVariable(null, "encoded", true) : dstVariableName;
 
-                string opType = "OneHotEncoder";
-                var node = ctx.CreateNode(opType, srcVariableName, encodedVariableName, ctx.GetNodeName(opType));
+                string opType = "Cast";
+                var castOutput = ctx.AddIntermediateVariable(info.TypeSrc, opType, true);
+                var castNode = ctx.CreateNode(opType, srcVariableName, castOutput, ctx.GetNodeName(opType), "");
+                castNode.AddAttribute("to", typeof(long));
+
+                opType = "OneHotEncoder";
+                var node = ctx.CreateNode(opType, castOutput, encodedVariableName, ctx.GetNodeName(opType));
                 node.AddAttribute("cats_int64s", Enumerable.Range(0, info.TypeSrc.GetItemType().GetKeyCountAsInt32(Host)).Select(x => (long)x));
                 node.AddAttribute("zeros", true);
                 if (_parent._columns[iinfo].OutputCountVector)
@@ -717,7 +717,6 @@ private bool SaveAsOnnxCore(OnnxContext ctx, int iinfo, ColInfo info, string src
                     reduceNode.AddAttribute("axes", new long[] { shape.Count - 1 });
                     reduceNode.AddAttribute("keepdims", 0);
                 }
-                return true;
             }
         }
     }

src/Microsoft.ML.Data/Transforms/ValueToKeyMappingTransformer.cs

@@ -768,22 +768,70 @@ protected override Delegate MakeGetter(DataViewRow input, int iinfo, Func<int, b
 
             private Delegate MakeGetter<T>(DataViewRow row, int src) => _termMap[src].GetMappingGetter(row);
 
+            private IEnumerable<T> GetTermsAndIds<T>(int iinfo, out long[] termIds)
+            {
+                var terms = default(VBuffer<T>);
+                var map = (TermMap<T>)_termMap[iinfo].Map;
+                map.GetTerms(ref terms);
+
+                var termValues = terms.DenseValues();
+                var keyMapper = map.GetKeyMapper();
+
+                int i = 0;
+                termIds = new long[map.Count];
+                foreach (var term in termValues)
+                {
+                    uint id = 0;
+                    keyMapper(term, ref id);
+                    termIds[i++] = id;
+                }
+                return termValues;
+            }
+
             private bool SaveAsOnnxCore(OnnxContext ctx, int iinfo, ColInfo info, string srcVariableName, string dstVariableName)
             {
-                if (!(info.TypeSrc.GetItemType() is TextDataViewType))
+                OnnxNode node;
+                long[] termIds;
+                string opType = "LabelEncoder";
+                var labelEncoderOutput = ctx.AddIntermediateVariable(_types[iinfo], "LabelEncoderOutput", true);
+
+                if (info.TypeSrc.GetItemType().Equals(TextDataViewType.Instance))
+                {
+                    node = ctx.CreateNode(opType, srcVariableName, labelEncoderOutput, ctx.GetNodeName(opType));
+                    var terms = GetTermsAndIds<ReadOnlyMemory<char>>(iinfo, out termIds);
+                    node.AddAttribute("keys_strings", terms);
+                }
+                else if (info.TypeSrc.GetItemType().Equals(NumberDataViewType.Single))
+                {
+                    node = ctx.CreateNode(opType, srcVariableName, labelEncoderOutput, ctx.GetNodeName(opType));
+                    var terms = GetTermsAndIds<float>(iinfo, out termIds);
+                    node.AddAttribute("keys_floats", terms);
+                }
+                else
+                {
+                    // LabelEncoder-2 in ORT v1 only supports the following mappings
+                    // int64-> float
+                    // int64-> string
+                    // float -> int64
+                    // float -> string
+                    // string -> int64
+                    // string -> float
+                    // In ML.NET the output of ValueToKeyMappingTransformer is always an integer type.
+                    // Therefore the only input types we can accept for Onnx conversion are strings and floats handled above.
                     return false;
+                }
 
-                var terms = default(VBuffer<ReadOnlyMemory<char>>);
-                TermMap<ReadOnlyMemory<char>> map = (TermMap<ReadOnlyMemory<char>>)_termMap[iinfo].Map;
-                map.GetTerms(ref terms);
-                string opType = "LabelEncoder";
-                var node = ctx.CreateNode(opType, srcVariableName, dstVariableName, ctx.GetNodeName(opType));
-                node.AddAttribute("classes_strings", terms.DenseValues());
                 node.AddAttribute("default_int64", -1);
-                //default_string needs to be an empty string but there is a BUG in Lotus that
-                //throws a validation error when default_string is empty. As a work around, set
-                //default_string to a space.
-                node.AddAttribute("default_string", " ");
+                node.AddAttribute("values_int64s", termIds);
+
+                // Onnx outputs an Int64, but ML.NET outputs a keytype. So cast it here
+                InternalDataKind dataKind;
+                InternalDataKindExtensions.TryGetDataKind(_parent._unboundMaps[iinfo].OutputType.RawType, out dataKind);
+
+                opType = "Cast";
+                var castNode = ctx.CreateNode(opType, labelEncoderOutput, dstVariableName, ctx.GetNodeName(opType), "");
+                castNode.AddAttribute("to", dataKind.ToType());
+
                 return true;
             }
 

src/Microsoft.ML.OnnxTransformer/OnnxUtils.cs

@@ -433,9 +433,8 @@ public static NamedOnnxValue CreateScalarNamedOnnxValue<T>(string name, T data)
                 throw new NotImplementedException($"Not implemented type {typeof(T)}");
 
             if (typeof(T) == typeof(ReadOnlyMemory<char>))
-            {
-                return NamedOnnxValue.CreateFromTensor<string>(name, new DenseTensor<string>(new string[] { data.ToString() }, new int[] { 1, 1 }, false));
-            }
+                return NamedOnnxValue.CreateFromTensor<string>(name, new DenseTensor<string>(new string[] { data.ToString() }, new int[] { 1, 1 }));
+
             return NamedOnnxValue.CreateFromTensor<T>(name, new DenseTensor<T>(new T[] { data }, new int[] { 1, 1 }));
         }
 
@@ -452,7 +451,19 @@ public static NamedOnnxValue CreateNamedOnnxValue<T>(string name, ReadOnlySpan<T
         {
             if (!_onnxTypeMap.Contains(typeof(T)))
                 throw new NotImplementedException($"Not implemented type {typeof(T)}");
-            return NamedOnnxValue.CreateFromTensor<T>(name, new DenseTensor<T>(data.ToArray(), shape.Select(x => (int)x).ToArray()));
+
+            var dimensions = shape.Select(x => (int)x).ToArray();
+
+            if (typeof(T) == typeof(ReadOnlyMemory<char>))
+            {
+                string[] stringData = new string[data.Length];
+                for (int i = 0; i < data.Length; i++)
+                    stringData[i] = data[i].ToString();
+
+                return NamedOnnxValue.CreateFromTensor<string>(name, new DenseTensor<string>(stringData, dimensions));
+            }
+
+            return NamedOnnxValue.CreateFromTensor<T>(name, new DenseTensor<T>(data.ToArray(), dimensions));
         }
 
         /// <summary>

src/Microsoft.ML.Transforms/Text/NgramTransform.cs

@@ -12,6 +12,7 @@
 using Microsoft.ML.CommandLine;
 using Microsoft.ML.Data;
 using Microsoft.ML.Internal.Utilities;
+using Microsoft.ML.Model.OnnxConverter;
 using Microsoft.ML.Runtime;
 using Microsoft.ML.Transforms.Text;
 
@@ -124,6 +125,7 @@ private sealed class TransformInfo
             public readonly bool[] NonEmptyLevels;
             public readonly int NgramLength;
             public readonly int SkipLength;
+            public readonly bool UseAllLengths;
             public readonly NgramExtractingEstimator.WeightingCriteria Weighting;
 
             public bool RequireIdf => Weighting == NgramExtractingEstimator.WeightingCriteria.Idf || Weighting == NgramExtractingEstimator.WeightingCriteria.TfIdf;
@@ -133,6 +135,7 @@ public TransformInfo(NgramExtractingEstimator.ColumnOptions info)
                 NgramLength = info.NgramLength;
                 SkipLength = info.SkipLength;
                 Weighting = info.Weighting;
+                UseAllLengths = info.UseAllLengths;
                 NonEmptyLevels = new bool[NgramLength];
             }
 
@@ -469,7 +472,7 @@ private protected override void SaveModel(ModelSaveContext ctx)
 
         private protected override IRowMapper MakeRowMapper(DataViewSchema schema) => new Mapper(this, schema);
 
-        private sealed class Mapper : OneToOneMapperBase
+        private sealed class Mapper : OneToOneMapperBase, ISaveAsOnnx
         {
             private readonly DataViewType[] _srcTypes;
             private readonly int[] _srcCols;
@@ -551,6 +554,81 @@ private void GetSlotNames(int iinfo, int size, ref VBuffer<ReadOnlyMemory<char>>
                 dst = dstEditor.Commit();
             }
 
+            private IEnumerable<long> GetNgramData(int iinfo, out long[] ngramCounts, out double[] weights, out List<long> indexes)
+            {
+                var transformInfo = _parent._transformInfos[iinfo];
+                var itemType = _srcTypes[iinfo].GetItemType();
+
+                Host.Assert(0 <= iinfo && iinfo < _parent.ColumnPairs.Length);
+                Host.Assert(InputSchema[_srcCols[iinfo]].HasKeyValues());
+
+                // Get the key values of the unigrams.
+                var keyCount = itemType.GetKeyCountAsInt32(Host);
+
+                var maxNGramLength = transformInfo.NgramLength;
+
+                var pool = _parent._ngramMaps[iinfo];
+
+                // the ngrams in ML.NET are sequentially organized. e.g. {a, a|b, b, b|c...}
+                // in onnx, they need to be separated by type. e.g. {a, b, c, a|b, b|c...}
+                // since the resulting vectors need to match, we need to create a mapping
+                // between the two and store it in the node attributes
+
+                // create seprate lists to track the ids of 1-grams, 2-grams etc
+                // because they need to be in adjacent regions in the same list
+                // when supplied to onnx
+                // We later concatenate all these separate n-gram lists
+                var ngramIds = new List<long>[maxNGramLength];
+                var ngramIndexes = new List<long>[maxNGramLength];
+                for (int i = 0; i < ngramIds.Length; i++)
+                {
+                    ngramIds[i] = new List<long>();
+                    ngramIndexes[i] = new List<long>();
+                    //ngramWeights[i] = new List<float>();
+                }
+
+                weights = new double[pool.Count];
+
+                uint[] ngram = new uint[maxNGramLength];
+                for (int i = 0; i < pool.Count; i++)
+                {
+                    var n = pool.GetById(i, ref ngram);
+                    Host.Assert(n >= 0);
+
+                    // add the id of each gram to the corresponding ids list
+                    for (int j = 0; j < n; j++)
+                        ngramIds[n - 1].Add(ngram[j]);
+
+                    // add the indexes to the corresponding list
+                    ngramIndexes[n - 1].Add(i);
+
+                    if (transformInfo.RequireIdf)
+                        weights[i] = _parent._invDocFreqs[iinfo][i];
+                    else
+                        weights[i] = 1.0f;
+                }
+
+                // initialize the ngramCounts array with start-index of each n-gram
+                int start = 0;
+                ngramCounts = new long[maxNGramLength];
+                for (int i = 0; i < maxNGramLength; i++)
+                {
+                    ngramCounts[i] = start;
+                    start += ngramIds[i].Count;
+                }
+
+                // concatenate all the lists and return
+                IEnumerable<long> allNGramIds = ngramIds[0];
+                indexes = ngramIndexes[0];
+                for (int i = 1; i < maxNGramLength; i++)
+                {
+                    allNGramIds = Enumerable.Concat(allNGramIds, ngramIds[i]);
+                    indexes = indexes.Concat(ngramIndexes[i]).ToList();
+                }
+
+                return allNGramIds;
+            }
+
             private void ComposeNgramString(uint[] ngram, int count, StringBuilder sb, int keyCount, in VBuffer<ReadOnlyMemory<char>> terms)
             {
                 Host.AssertValue(sb);
@@ -660,6 +738,84 @@ protected override Delegate MakeGetter(DataViewRow input, int iinfo, Func<int, b
                 }
                 return del;
             }
+
+            public bool CanSaveOnnx(OnnxContext ctx) => true;
+
+            public void SaveAsOnnx(OnnxContext ctx)
+            {
+                Host.CheckValue(ctx, nameof(ctx));
+
+                int numColumns = _parent.ColumnPairs.Length;
+                for (int iinfo = 0; iinfo < numColumns; ++iinfo)
+                {
+                    string inputColumnName = _parent.ColumnPairs[iinfo].inputColumnName;
+                    if (!ctx.ContainsColumn(inputColumnName))
+                        continue;
+
+                    string outputColumnName = _parent.ColumnPairs[iinfo].outputColumnName;
+                    string dstVariableName = ctx.AddIntermediateVariable(_srcTypes[iinfo], outputColumnName, true);
+                    SaveAsOnnxCore(ctx, iinfo, ctx.GetVariableName(inputColumnName), dstVariableName);
+                }
+            }
+
+            private void SaveAsOnnxCore(OnnxContext ctx, int iinfo, string srcVariableName, string dstVariableName )
+            {
+                VBuffer<ReadOnlyMemory<char>> slotNames = default;
+                GetSlotNames(iinfo, 0, ref slotNames);
+
+                var transformInfo = _parent._transformInfos[iinfo];
+
+                // TfIdfVectorizer accepts strings, int32 and int64 tensors.
+                // But in the ML.NET implementation of the NGramTransform, it only accepts keys as inputs
+                // That are the result of ValueToKeyMapping transformer, which outputs UInt32 values
+                // So, if it is UInt32 or UInt64, cast the output here to Int32/Int64
+                string opType;
+                var vectorType = _srcTypes[iinfo] as VectorDataViewType;
+
+                if ((vectorType != null) &&
+                    ((vectorType.RawType == typeof(VBuffer<UInt32>)) || (vectorType.RawType == typeof(VBuffer<UInt64>))))
+                {
+                    var dataKind = _srcTypes[iinfo] == NumberDataViewType.UInt32 ? DataKind.Int32 : DataKind.Int64;
+
+                    opType = "Cast";
+                    string castOutput = ctx.AddIntermediateVariable(_srcTypes[iinfo], "CastOutput", true);
+
+                    var castNode = ctx.CreateNode(opType, srcVariableName, castOutput, ctx.GetNodeName(opType), "");
+                    var t = InternalDataKindExtensions.ToInternalDataKind(dataKind).ToType();
+                    castNode.AddAttribute("to", t);
+
+                    srcVariableName = castOutput;
+                }
+
+                opType = "TfIdfVectorizer";
+                var node = ctx.CreateNode(opType, srcVariableName, dstVariableName, ctx.GetNodeName(opType), "");
+                node.AddAttribute("max_gram_length", transformInfo.NgramLength);
+                node.AddAttribute("max_skip_count", transformInfo.SkipLength);
+                node.AddAttribute("min_gram_length", transformInfo.UseAllLengths ? 1 : transformInfo.NgramLength);
+
+                string mode;
+                if (transformInfo.RequireIdf)
+                {
+                    mode = transformInfo.Weighting == NgramExtractingEstimator.WeightingCriteria.Idf ? "IDF" : "TFIDF";
+                }
+                else
+                {
+                    mode = "TF";
+                }
+                node.AddAttribute("mode", mode);
+
+                long[] ngramCounts;
+                double[] ngramWeights;
+                List<long> ngramIndexes;
+
+                var ngramIds = GetNgramData(iinfo, out ngramCounts, out ngramWeights, out ngramIndexes);
+
+                node.AddAttribute("ngram_counts", ngramCounts);
+                node.AddAttribute("pool_int64s", ngramIds);
+                node.AddAttribute("ngram_indexes", ngramIndexes);
+                node.AddAttribute("weights", ngramWeights);
+            }
+
         }
     }