ComputeCost() public method

Compute the error cost of the given Theta parameter for the training and label sets
public ComputeCost ( Vector theta ) : double
theta numl.Math.LinearAlgebra.Vector Learning Theta parameters
return double
LogisticCostFunction Class Documentation
コード例 #1
0
        public void Logistic_Regression_Test_CostFunction_2_WithoutRegularization()
        {
            Matrix X = new[,] {
             { 8, 1, 6 },
             { 3, 5 ,7 },
             { 4, 9, 2 }};

            Vector y = new Vector(new double[] { 1, 1, 0 });
            Vector theta = new Vector(new double[] { 0, 1, 0 });

            ICostFunction logisticCostFunction = new LogisticCostFunction()
            {
                X = X,
                Y = y,
                Lambda = 0,
            };

            double cost = logisticCostFunction.ComputeCost(theta.Copy());

            theta = logisticCostFunction.ComputeGradient(theta.Copy());

            Assert.Equal(3.1067d, System.Math.Round(cost, 4));

            Assert.Equal(0.6093d, System.Math.Round(theta[0], 4));
            Assert.Equal(2.8988d, System.Math.Round(theta[1], 4));
            Assert.Equal(0.1131d, System.Math.Round(theta[2], 4));
        }
コード例 #2
0
        public void Logistic_Regression_Test_CostFunction_1()
        {
            Matrix X = new[,]
            {{ 1, 1, 1 },
             { 1, 1, 1 },
             { 1, 1, 1 },
             { 8, 1, 6 },
             { 3, 5 ,7 },
             { 4, 9, 2 }};

            Vector y = new Vector(new double[] { 1, 0, 1, 0, 1, 0 });
            Vector theta = new Vector(new double[] { 0, 1, 0 });

            ICostFunction logisticCostFunction = new LogisticCostFunction()
            {
                X = X,
                Y = y,
                Lambda = 3,
                Regularizer = new L2Regularizer()
            };

            double cost = logisticCostFunction.ComputeCost(theta.Copy());

            theta = logisticCostFunction.ComputeGradient(theta.Copy());

            Assert.Equal(2.2933d, System.Math.Round(cost, 4));

            Assert.Equal(1.6702d, System.Math.Round(theta[0], 4));
            Assert.Equal(2.1483d, System.Math.Round(theta[1], 4));
            Assert.Equal(1.0887d, System.Math.Round(theta[2], 4));
        }