Add GlobalMaxPool1D, GlobalMaxPool2D, GlobalMaxPool3D (#76)

Author: Shashi456

Sources/TensorFlow/Layers/Pooling.swift

@@ -340,3 +340,54 @@ public struct GlobalAvgPool3D<Scalar: TensorFlowFloatingPoint>: Layer {
         return input.mean(squeezingAxes: [1, 2, 3])
     }
 }
+
+/// A global max pooling layer for temporal data.
+@_fixed_layout
+public struct GlobalMaxPool1D<Scalar: TensorFlowFloatingPoint>: Layer {
+    /// Creates a global max pooling layer.
+    public init() {}
+
+    /// Returns the output obtained from applying the layer to the given input.
+    ///
+    /// - Parameters:
+    ///   - input: The input to the layer.
+    ///   - context: The contextual information for the layer application, e.g. the current learning
+    ///     phase.
+    /// - Returns: The output.
+    @differentiable
+    public func call(_ input: Tensor<Scalar>) -> Tensor<Scalar> {
+        return input.max(squeezingAxes: 1)
+    }
+}
+
+/// A global max pooling layer for spatial data.
+@_fixed_layout
+public struct GlobalMaxPool2D<Scalar: TensorFlowFloatingPoint>: Layer {
+    /// Creates a global max pooling layer.
+    public init() {}
+
+    /// Returns the output obtained from applying the layer to the given input.
+    ///
+    /// - Parameter input: The input to the layer.
+    /// - Returns: The output.
+    @differentiable
+    public func call(_ input: Tensor<Scalar>) -> Tensor<Scalar> {
+        return input.max(squeezingAxes: [1, 2])
+    }
+}
+
+/// A global max pooling layer for spatial and spatio-temporal data.
+@_fixed_layout
+public struct GlobalMaxPool3D<Scalar: TensorFlowFloatingPoint>: Layer {
+    /// Creates a global max pooling layer.
+    public init() {}
+
+    /// Returns the output obtained from applying the layer to the given input.
+    ///
+    /// - Parameter input: The input to the layer.
+    /// - Returns: The output.
+    @differentiable
+    public func call(_ input: Tensor<Scalar>) -> Tensor<Scalar> {
+        return input.max(squeezingAxes: [1, 2, 3])
+    }
+}

Tests/TensorFlowTests/LayerTests.swift

@@ -124,6 +124,30 @@ final class LayerTests: XCTestCase {
         XCTAssertEqual(output, expected)
     }
 
+    func testGlobalMaxPool1D() {
+        let layer = GlobalMaxPool1D<Float>()
+        let input = Tensor(shape: [1, 10, 1], scalars: (0..<10).map(Float.init))
+        let output = layer.inferring(from: input)
+        let expected = Tensor<Float>([9])
+        XCTAssertEqual(output, expected)
+    }
+
+    func testGlobalMaxPool2D() {
+        let layer = GlobalMaxPool2D<Float>()
+        let input = Tensor(shape: [1, 2, 10, 1], scalars: (0..<20).map(Float.init))
+        let output = layer.inferring(from: input)
+        let expected = Tensor<Float>([19])
+        XCTAssertEqual(output, expected)
+    }
+
+    func testGlobalMaxPool3D() {
+        let layer = GlobalMaxPool3D<Float>()
+        let input = Tensor<Float>(shape: [1, 2, 3, 5, 1], scalars: (0..<30).map(Float.init))
+        let output = layer.inferring(from: input)
+        let expected = Tensor<Float>([29])
+        XCTAssertEqual(output, expected)
+    }
+
     func testUpSampling1D() {
       let size = 6
       let layer = UpSampling1D<Float>(size: size)
@@ -226,6 +250,9 @@ final class LayerTests: XCTestCase {
         ("testGlobalAvgPool1D", testGlobalAvgPool1D),
         ("testGlobalAvgPool2D", testGlobalAvgPool2D),
         ("testGlobalAvgPool3D", testGlobalAvgPool3D),
+        ("testGlobalMaxPool1D", testGlobalMaxPool1D),
+        ("testGlobalMaxPool2D", testGlobalMaxPool2D),
+        ("testGlobalMaxPool3D", testGlobalMaxPool3D),
         ("testUpSampling1D", testUpSampling1D),
         ("testUpSampling2D", testUpSampling2D),
         ("testUpSampling3D", testUpSampling3D),