fix: Implemented support for loading models with Concatenate layers

src/TensorFlowNET.Core/Keras/ArgsDefinition/Merging/MergeArgs.cs

@@ -1,13 +1,15 @@
-using System;
+using Newtonsoft.Json;
+using System;
 using System.Collections.Generic;
 using System.Text;
 
 namespace Tensorflow.Keras.ArgsDefinition
 {
     // TODO: complete the implementation
-    public class MergeArgs : LayerArgs
+    public class MergeArgs : AutoSerializeLayerArgs
     {
         public Tensors Inputs { get; set; }
+        [JsonProperty("axis")]
         public int Axis { get; set; }
     }
 }

src/TensorFlowNET.Core/NumPy/Numpy.Manipulation.cs

@@ -30,6 +30,15 @@ public static NDArray concatenate((NDArray, NDArray) tuple, int axis = 0)
         [AutoNumPy]
         public static NDArray stack(params NDArray[] arrays) => new NDArray(array_ops.stack(arrays));
 
+        [AutoNumPy]
+        public static NDArray stack(NDArray[] arrays, int axis = 0) => new NDArray(array_ops.stack(arrays, axis));
+
+        [AutoNumPy]
+        public static NDArray stack((NDArray, NDArray) tuple, int axis = 0) => new NDArray(array_ops.stack(new[] { tuple.Item1, tuple.Item2 }, axis));
+
+        [AutoNumPy]
+        public static NDArray stack((NDArray, NDArray, NDArray) tuple, int axis = 0) => new NDArray(array_ops.stack(new[] { tuple.Item1, tuple.Item2, tuple.Item3 }, axis));
+
         [AutoNumPy]
         public static NDArray moveaxis(NDArray array, Axis source, Axis destination) => new NDArray(array_ops.moveaxis(array, source, destination));
     }

src/TensorFlowNET.Keras/Engine/Functional.FromConfig.cs

@@ -30,7 +30,7 @@ public static (Tensors, Tensors, Dictionary<string, ILayer>) reconstruct_from_co
             created_layers = created_layers ?? new Dictionary<string, ILayer>();
             var node_index_map = new Dictionary<(string, int), int>();
             var node_count_by_layer = new Dictionary<ILayer, int>();
-            var unprocessed_nodes = new Dictionary<ILayer, NodeConfig>();
+            var unprocessed_nodes = new Dictionary<ILayer, List<NodeConfig>>();
             // First, we create all layers and enqueue nodes to be processed
             foreach (var layer_data in config.Layers)
                 process_layer(created_layers, layer_data, unprocessed_nodes, node_count_by_layer);
@@ -79,7 +79,7 @@ public static (Tensors, Tensors, Dictionary<string, ILayer>) reconstruct_from_co
 
         static void process_layer(Dictionary<string, ILayer> created_layers, 
             LayerConfig layer_data, 
-            Dictionary<ILayer, NodeConfig> unprocessed_nodes,
+            Dictionary<ILayer, List<NodeConfig>> unprocessed_nodes,
             Dictionary<ILayer, int> node_count_by_layer)
         {
             ILayer layer = null;
@@ -92,32 +92,38 @@ static void process_layer(Dictionary<string, ILayer> created_layers,
 
                 created_layers[layer_name] = layer;
             }
-            node_count_by_layer[layer] = _should_skip_first_node(layer) ? 1 : 0;
+            node_count_by_layer[layer] = layer_data.InboundNodes.Count - (_should_skip_first_node(layer) ? 1 : 0);
 
             var inbound_nodes_data = layer_data.InboundNodes;
             foreach (var node_data in inbound_nodes_data)
             {
                 if (!unprocessed_nodes.ContainsKey(layer))
-                    unprocessed_nodes[layer] = node_data;
+                    unprocessed_nodes[layer] = new List<NodeConfig>() { node_data };
                 else
-                    unprocessed_nodes.Add(layer, node_data);
+                    unprocessed_nodes[layer].Add(node_data);
             }
         }
 
         static void process_node(ILayer layer, 
-            NodeConfig node_data, 
+            List<NodeConfig> nodes_data, 
             Dictionary<string, ILayer> created_layers,
             Dictionary<ILayer, int> node_count_by_layer,
             Dictionary<(string, int), int> node_index_map)
         {
+
             var input_tensors = new List<Tensor>();
-            var inbound_layer_name = node_data.Name;
-            var inbound_node_index = node_data.NodeIndex;
-            var inbound_tensor_index = node_data.TensorIndex;
 
-            var inbound_layer = created_layers[inbound_layer_name];
-            var inbound_node = inbound_layer.InboundNodes[inbound_node_index];
-            input_tensors.Add(inbound_node.Outputs[inbound_node_index]);
+            for (int i = 0; i < nodes_data.Count; i++)
+            {
+                var node_data = nodes_data[i];
+                var inbound_layer_name = node_data.Name;
+                var inbound_node_index = node_data.NodeIndex;
+                var inbound_tensor_index = node_data.TensorIndex;
+
+                var inbound_layer = created_layers[inbound_layer_name];
+                var inbound_node = inbound_layer.InboundNodes[inbound_node_index];
+                input_tensors.Add(inbound_node.Outputs[inbound_node_index]);
+            }
 
             var output_tensors = layer.Apply(input_tensors);
 

src/TensorFlowNET.Keras/Layers/Merging/Concatenate.cs

@@ -39,6 +39,7 @@ public override void build(KerasShapesWrapper input_shape)
                 shape_set.Add(shape);
             }*/
             _buildInputShape = input_shape;
+            built = true;
         }
 
         protected override Tensors _merge_function(Tensors inputs)

src/TensorFlowNET.Keras/Utils/generic_utils.cs

@@ -112,12 +112,23 @@ public static FunctionalConfig deserialize_model_config(JToken json)
             foreach (var token in layersToken)
             {
                 var args = deserialize_layer_args(token["class_name"].ToObject<string>(), token["config"]);
+
+                List<NodeConfig> nodeConfig = null; //python tensorflow sometimes exports inbound nodes in an extra nested array
+                if (token["inbound_nodes"].Count() > 0 && token["inbound_nodes"][0].Count() > 0 && token["inbound_nodes"][0][0].Count() > 0)
+                {
+                    nodeConfig = token["inbound_nodes"].ToObject<List<List<NodeConfig>>>().FirstOrDefault() ?? new List<NodeConfig>();
+                }
+                else
+                {
+                    nodeConfig = token["inbound_nodes"].ToObject<List<NodeConfig>>();
+                }
+
                 config.Layers.Add(new LayerConfig()
                 {
                     Config = args, 
                     Name = token["name"].ToObject<string>(), 
                     ClassName = token["class_name"].ToObject<string>(), 
-                    InboundNodes = token["inbound_nodes"].ToObject<List<NodeConfig>>()
+                    InboundNodes = nodeConfig,
                 });
             }
             config.InputLayers = json["input_layers"].ToObject<List<NodeConfig>>();

test/TensorFlowNET.Keras.UnitTest/Layers/Layers.Merging.Test.cs

@@ -1,4 +1,5 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System.Collections.Generic;
 using Tensorflow.NumPy;
 using static Tensorflow.KerasApi;
 
@@ -8,12 +9,16 @@ namespace Tensorflow.Keras.UnitTest.Layers
     public class LayersMergingTest : EagerModeTestBase
     {
         [TestMethod]
-        public void Concatenate()
+        [DataRow(1, 4, 1, 5)]
+        [DataRow(2, 2, 2, 5)]
+        [DataRow(3, 2, 1, 10)]
+        public void Concatenate(int axis, int shapeA, int shapeB, int shapeC)
         {
-            var x = np.arange(20).reshape((2, 2, 5));
-            var y = np.arange(20, 30).reshape((2, 1, 5));
-            var z = keras.layers.Concatenate(axis: 1).Apply(new Tensors(x, y));
-            Assert.AreEqual((2, 3, 5), z.shape);
+            var x = np.arange(10).reshape((1, 2, 1, 5));
+            var y = np.arange(10, 20).reshape((1, 2, 1, 5));
+            var z = keras.layers.Concatenate(axis: axis).Apply(new Tensors(x, y));
+            Assert.AreEqual((1, shapeA, shapeB, shapeC), z.shape);
         }
+
     }
 }

test/TensorFlowNET.Keras.UnitTest/Model/ModelLoadTest.cs

@@ -1,10 +1,13 @@
 using Microsoft.VisualStudio.TestPlatform.Utilities;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Newtonsoft.Json.Linq;
 using System.Linq;
+using System.Xml.Linq;
 using Tensorflow.Keras.Engine;
 using Tensorflow.Keras.Optimizers;
 using Tensorflow.Keras.UnitTest.Helpers;
 using Tensorflow.NumPy;
+using static HDF.PInvoke.H5Z;
 using static Tensorflow.Binding;
 using static Tensorflow.KerasApi;
 
@@ -124,4 +127,44 @@ public void TestModelBeforeTF2_5()
         var model = tf.saved_model.load(@"D:\development\temp\saved_model") as Tensorflow.Keras.Engine.Model;
         model.summary();
     }
+
+
+
+    [TestMethod]
+    public void CreateConcatenateModelSaveAndLoad()
+    {
+        // a small demo model that is just here to see if the axis value for the concatenate method is saved and loaded.
+        var input_layer = tf.keras.layers.Input((8, 8, 5));
+
+        var conv1 = tf.keras.layers.Conv2D(2, kernel_size: 3, activation: "relu", padding: "same"/*, data_format: "_conv_1"*/).Apply(input_layer);
+        conv1.Name = "conv1";
+
+        var conv2 = tf.keras.layers.Conv2D(2, kernel_size: 3, activation: "relu", padding: "same"/*, data_format: "_conv_2"*/).Apply(input_layer);
+        conv2.Name = "conv2";
+
+        var concat1 = tf.keras.layers.Concatenate(axis: 3).Apply((conv1, conv2));
+        concat1.Name = "concat1";
+
+        var model = tf.keras.Model(input_layer, concat1);
+        model.compile(tf.keras.optimizers.Adam(), tf.keras.losses.CategoricalCrossentropy());
+
+        model.save(@"Assets/concat_axis3_model");
+
+
+        var tensorInput = np.arange(320).reshape((1, 8, 8, 5)).astype(TF_DataType.TF_FLOAT);
+
+        var tensors1 = model.predict(tensorInput);
+
+        Assert.AreEqual((1, 8, 8, 4), tensors1.shape);
+
+        model = null;
+        keras.backend.clear_session();
+
+        var model2 = tf.keras.models.load_model(@"Assets/concat_axis3_model");
+
+        var tensors2 = model2.predict(tensorInput);
+
+        Assert.AreEqual(tensors1.shape, tensors2.shape);
+    }
+
 }