merging master

Author: Shashi456

Sources/TensorFlow/Loss.swift

@@ -48,16 +48,25 @@ public func hingeLoss<Scalar: TensorFlowFloatingPoint>(
     return max(Tensor(1) - expected * predicted, Tensor(0)).mean()
 }
 
-/// Returns the squared hinge loss between predictions and expectations.
+@differentiable(wrt: predicted)
+public func squaredHingeLoss<Scalar: TensorFlowFloatingPoint>(
+    predicted: Tensor<Scalar>, expected: Tensor<Scalar>
+) -> Tensor<Scalar> {
+    return (max(Tensor(1) - expected * predicted, Tensor(0))).squared().mean()
+}
+
+/// Returns the hinge loss between predictions and expectations.
 ///
 /// - Parameters:
 ///   - predicted: Predicted outputs from a neural network.
 ///   - expected: Expected values, i.e. targets, that correspond to the correct output.
 @differentiable(wrt: predicted)
-public func squaredHingeLoss<Scalar: TensorFlowFloatingPoint>(
+public func categoricalHingeLoss<Scalar: TensorFlowFloatingPoint>(
     predicted: Tensor<Scalar>, expected: Tensor<Scalar>
 ) -> Tensor<Scalar> {
-    return (max(Tensor(1) - expected * predicted, Tensor(0))).squared().mean()
+    let positive = (expected * predicted).sum()
+    let negative = ((Tensor(1) - expected) * predicted).max()
+    return max(Tensor(0), negative - positive + Tensor(1))
 }
 
 /// Computes the softmax cross entropy (categorical cross entropy) between logits and labels.

Tests/TensorFlowTests/LossTests.swift

@@ -76,6 +76,15 @@ final class LossTests: XCTestCase {
         assertElementsEqual(expected: Tensor(expectedLoss), actual: loss)
     }
 
+    func testCategoricalHingeLoss() {
+        let predicted = Tensor<Float>([3, 4 ,5])
+        let expected = Tensor<Float>([0.3, 0.4, 0.3])
+
+        let loss = categoricalHingeLoss(predicted: predicted, expected: expected)
+        let expectedLoss: Float = 0.5
+        assertElementsEqual(expected: Tensor(expectedLoss), actual: loss)
+    }
+
     func testSoftmaxCrossEntropyWithProbabilitiesLoss() {
         let logits = Tensor<Float>(shape: [2, 4], scalars: [1, 2, 3, 4, 5, 6, 7, 8])
         let labels = Tensor<Float>(
@@ -168,6 +177,8 @@ final class LossTests: XCTestCase {
     static var allTests = [
         ("testMeanSquaredErrorLoss", testMeanSquaredErrorLoss),
         ("testMeanSquaredErrorGrad", testMeanSquaredErrorGrad),
+        ("testHingeLoss", testHingeLoss),
+        ("testCategoricalHingeLoss", testCategoricalHingeLoss),
         ("testSquaredHingeLoss", testSquaredHingeLoss),
         ("testSoftmaxCrossEntropyWithProbabilitiesLoss",
          testSoftmaxCrossEntropyWithProbabilitiesLoss),