Adjusted implementation of Gather to correspond to Python implementation.

Added minval, maxval, and seed arguments to the RandomUniformInitializer
Added unit tests for Gather and a simple Embedding test.

Author: NiklasGustafsson

src/TensorFlowNET.Core/Operations/Initializers/RandomUniform.cs

@@ -18,20 +18,17 @@ namespace Tensorflow.Operations.Initializers
 {
     public class RandomUniform : IInitializer
     {
-#pragma warning disable CS0649 // Field 'RandomUniform.seed' is never assigned to, and will always have its default value
         private int? seed;
-#pragma warning restore CS0649 // Field 'RandomUniform.seed' is never assigned to, and will always have its default value
-#pragma warning disable CS0649 // Field 'RandomUniform.minval' is never assigned to, and will always have its default value 0
         private float minval;
-#pragma warning restore CS0649 // Field 'RandomUniform.minval' is never assigned to, and will always have its default value 0
-#pragma warning disable CS0649 // Field 'RandomUniform.maxval' is never assigned to, and will always have its default value 0
         private float maxval;
-#pragma warning restore CS0649 // Field 'RandomUniform.maxval' is never assigned to, and will always have its default value 0
         private TF_DataType dtype;
 
-        public RandomUniform(TF_DataType dtype = TF_DataType.TF_FLOAT)
+        public RandomUniform(TF_DataType dtype = TF_DataType.TF_FLOAT, float minval = -0.05f, float maxval = 0.05f, int? seed = null)
         {
             this.dtype = dtype;
+            this.minval = minval;
+            this.maxval = maxval;
+            this.seed = seed;
         }
 
         public Tensor Apply(InitializerArgs args)

src/TensorFlowNET.Core/Operations/gen_array_ops.cs

@@ -119,11 +119,43 @@ public static Tensor expand_dims(Tensor input, int axis, string name = null)
 
         public static Tensor gather_v2<T1, T2>(T1 @params, T2 indices, int axis, string name = null)
         {
+            if (tf.Context.executing_eagerly())
+            {
+                try
+                {
+                    var results = tf.Runner.TFE_FastPathExecute(new FastPathOpExecInfo("GatherV2", name, @params, indices, axis, "batch_dims")
+                    {
+                        ctx = tf.Context,
+                        device_name = tf.Context.DeviceName
+                    });
+                    return results[0];
+                }
+                catch (Exception exc)
+                {
+                    return gather_v2_eager_fallback(@params, indices, axis, name, tf.Context);
+                }
+            }
+
             var _op = tf.OpDefLib._apply_op_helper("GatherV2", name: name, new { @params, indices, axis });
 
             return _op.outputs[0];
         }
 
+        private static Tensor gather_v2_eager_fallback(object @params, object indices, int axis, string name, Context ctx)
+        {
+            var (_attr_T, param) = tf.Runner.ArgsToMatchingEager(ctx, args: new[] { @params });
+            var (_attr_Tindice, indice) = tf.Runner.ArgsToMatchingEager(ctx, default_dtype: tf.int32, args: new[] { indices });
+            var (_attr_Taxis, axiss) = tf.Runner.ArgsToMatchingEager(ctx, default_dtype: tf.int32, args: new object[] { axis });
+            var _inputs_flat = param.concat(indice).concat(axiss);
+            var _attrs = new object[] { "batch_dims", 0, "Tparams", _attr_T, "Tindices", _attr_Tindice, "Taxis", _attr_Taxis };
+
+            var results = tf.Runner.Execute(ctx, "GatherV2", 1, _inputs_flat, _attrs, name: name);
+            if (tf.Runner.MustRecordGradient())
+                tf.Runner.RecordGradient("GatherV2", _inputs_flat, _attrs, results);
+            return results[0];
+        }
+
+
         public static Tensor pad(Tensor input, Tensor paddings, string name = null)
         {
             if (tf.Context.executing_eagerly())

src/TensorFlowNET.Keras/Layers/Core/Embedding.cs

@@ -48,7 +48,7 @@ public Embedding(EmbeddingArgs args)
             if (args.BatchInputShape == null)
                 args.BatchInputShape = new int[] { args.BatchSize }.Concat(args.InputShape.dims).ToArray();
 
-            embeddings_initializer = embeddings_initializer ?? tf.random_uniform_initializer;
+            embeddings_initializer = args.EmbeddingsInitializer ?? tf.random_uniform_initializer;
             SupportsMasking = mask_zero;
         }
 

test/TensorFlowNET.Keras.UnitTest/Layers/LayersTest.cs

@@ -1,6 +1,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using NumSharp;
 using Tensorflow;
+using Tensorflow.Operations.Initializers;
 using static Tensorflow.Binding;
 using static Tensorflow.KerasApi;
 
@@ -60,13 +61,26 @@ public void TensorFlowOpLayer()
             Assert.AreEqual(model.Layers.Count, 8);
             var result = model.predict(tf.constant(np.arange(24).astype(np.float32)[np.newaxis, Slice.All]));
             Assert.AreEqual(result.shape, new TensorShape(1, 24));
-            model.fit(np.arange(24).astype(np.float32)[np.newaxis, Slice.All], np.arange(24).astype(np.float32)[np.newaxis, Slice.All], verbose: 0); 
+            model.fit(np.arange(24).astype(np.float32)[np.newaxis, Slice.All], np.arange(24).astype(np.float32)[np.newaxis, Slice.All], verbose: 0);
         }
 
         /// <summary>
         /// https://www.tensorflow.org/api_docs/python/tf/keras/layers/Embedding
         /// </summary>
-        [TestMethod, Ignore]
+        [TestMethod]
+        public void Embedding_Simple()
+        {
+            var emb = keras.layers.Embedding(256, 12, input_length: 4);
+            var input_array = np.arange(12).reshape(3, 4).astype(np.float32);
+            var output = emb.Apply(input_array);
+            Assert.AreEqual(new TensorShape(3, 4, 12), output.shape);
+        }
+
+        /// <summary>
+        /// https://www.tensorflow.org/api_docs/python/tf/keras/layers/Embedding
+        /// </summary>
+        [TestMethod]
+        [Ignore]
         public void Embedding()
         {
             var model = keras.Sequential();

test/TensorFlowNET.UnitTest/ManagedAPI/ArrayOpsTest.cs

@@ -0,0 +1,27 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using NumSharp;
+using Tensorflow;
+using static Tensorflow.Binding;
+
+namespace TensorFlowNET.UnitTest.ManagedAPI
+{
+    [TestClass]
+    public class ArrayOpsTest : EagerModeTestBase
+    { 
+        /// <summary>
+        /// https://www.tensorflow.org/api_docs/python/tf/keras/layers/Embedding
+        /// </summary>
+        [TestMethod]
+        public void Gather()
+        {
+            var input_array = tf.constant(np.arange(12).reshape(3, 4).astype(np.float32));
+            var indices = tf.constant(np.array(new int[] { 0, 2 }));
+
+            var result = array_ops.gather(input_array, indices);
+            Assert.AreEqual(new TensorShape(2, 4), result.shape);
+            Assert.AreEqual(result.numpy()[0,0], 0.0f);
+            Assert.AreEqual(result.numpy()[0,1], 1.0f);
+            Assert.AreEqual(result.numpy()[1,3], 11.0f);
+        }
+    }
+}