public void BaselineHazardTestR()
        {
            double[,] data =
            {
                // t   c  in
                {  8, 0, 13 },
                {  4, 1, 56 },
                { 12, 0, 25 },
                {  6, 0, 64 },
                { 10, 0, 38 },
                {  8, 1, 80 },
                {  5, 0,  0 },
                {  5, 0, 81 },
                {  3, 1, 81 },
                { 14, 1, 38 },
                {  8, 0, 23 },
                { 11, 0, 99 },
                {  7, 0, 12 },
                {  7, 1, 36 },
                { 12, 0, 63 },
                {  8, 0, 92 },
                {  7, 0, 38 },
            };


            double[]          time   = data.GetColumn(0);
            SurvivalOutcome[] censor = data.GetColumn(1).To <SurvivalOutcome[]>();
            double[][]        inputs = data.GetColumn(2).ToArray();

            var regression = new ProportionalHazards(1);

            var target = new ProportionalHazardsNewtonRaphson(regression);

            double error = target.Run(inputs, time, censor);

            // Assert.AreEqual(-10.257417973830666, error, 1e-8);

            /*
             * library('survival')
             * options(digits=17)
             * time <- c(8, 4, 12, 6, 10, 8, 5, 5, 3, 14, 8, 11, 7, 7, 12, 8, 7)
             * x <- c(13, 56, 25, 64, 38, 80, 0, 81, 81, 38, 23, 99, 12, 36, 63, 92, 38)
             * c <- c(0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0)
             *
             * fit <- coxph(Surv(time, c) ~ x, ties="breslow")
             *
             * predict(fit,type="risk")
             *
             * fit$loglik
             *
             *      coef           exp(coef)          se(coef)               z              p
             * x 0.01633097532122  1.016465054586   0.01711960930183    0.9539338797573   0.340117112635
             *
             * Likelihood ratio test=0.94  on 1 df, p=0.332836850925  n= 17, number of events= 5
             */

            // Tested against GNU R
            Assert.AreEqual(49.352941176470587, regression.Offsets[0]);
            Assert.AreEqual(0.01633097532122, regression.Coefficients[0], 1e-10);
            Assert.AreEqual(0.01711960930183, regression.StandardErrors[0], 1e-10);
            Assert.AreEqual(0.340117112635, regression.GetWaldTest(0).PValue, 1e-5);
            Assert.AreEqual(-10.2879332934202168, regression.GetPartialLogLikelihood(time, censor));
            Assert.AreEqual(-9.8190189050165948, regression.GetPartialLogLikelihood(inputs, time, censor));

            double[] actual = inputs.Apply(regression.Compute);

            /*
             * predict(r,type="risk")
             *  [1] 0.55229166964915244 1.11466393245000361 0.67185866444081555 1.27023351821156782 0.83076808526813917 1.64953983529334769 0.44664925161695829 1.67669959872327912
             *  [9] 1.67669959872327912 0.83076808526813917 0.65026895029003673 2.24967304521214029 0.54334545703992021 0.80407192663266613 1.24965783376477391 2.00665280971219540
             *  [17] 0.83076808526813917
             */

            double[] expected =
            {
                0.55229166964915244, 1.11466393245000361, 0.67185866444081555, 1.27023351821156782,
                0.83076808526813917, 1.64953983529334769, 0.44664925161695829, 1.67669959872327912,
                1.67669959872327912, 0.83076808526813917, 0.65026895029003673, 2.24967304521214029,
                0.54334545703992021, 0.80407192663266613, 1.24965783376477391, 2.00665280971219540,
                0.83076808526813917
            };

            for (int i = 0; i < actual.Length; i++)
            {
                Assert.AreEqual(expected[i], actual[i], 0.025);
            }
        }
        public void BaselineHazardTest()
        {
            double[,] data =
            {
                // t   c  in
                {  8, 0, 13 },
                {  4, 1, 56 },
                { 12, 0, 25 },
                {  6, 0, 64 },
                { 10, 0, 38 },
                {  8, 1, 80 },
                {  5, 0,  0 },
                {  5, 0, 81 },
                {  3, 1, 81 },
                { 14, 1, 38 },
                {  8, 0, 23 },
                { 11, 0, 99 },
                {  7, 0, 12 },
                {  7, 1, 36 },
                { 12, 0, 63 },
                {  8, 0, 92 },
                {  7, 0, 38 },
            };

            double[]   time   = data.GetColumn(0);
            int[]      censor = data.GetColumn(1).ToInt32();
            double[][] inputs = data.GetColumn(2).ToArray();

            ProportionalHazards regression = new ProportionalHazards(1);

            ProportionalHazardsNewtonRaphson target = new ProportionalHazardsNewtonRaphson(regression);

            target.Normalize = false;

            double error = target.Run(inputs, time, censor);
            double log   = -2 * regression.GetPartialLogLikelihood(inputs, time, censor);

            EmpiricalHazardDistribution baseline = regression.BaselineHazard as EmpiricalHazardDistribution;

            double[] actual = new double[(int)baseline.Support.Max];
            for (int i = (int)baseline.Support.Min; i < baseline.Support.Max; i++)
            {
                actual[i] = baseline.CumulativeHazardFunction(i);
            }

            Assert.AreEqual(14, actual.Length);

            double[] expected =
            {
                0,                                       0,                    0,
                0.025000345517572315, 0.052363663484639708, 0.052363663484639708, 0.052363663484639708,
                0.16317880290786446,
                0.34217461190678861,   0.34217461190678861,  0.34217461190678861,
                0.34217461190678861,   0.34217461190678861, 0.34217461190678861
            };

            for (int i = 0; i < actual.Length; i++)
            {
                Assert.AreEqual(expected[i], actual[i], 0.025);
            }
        }
        public void PredictTest1()
        {
            // Data from: http://statpages.org/prophaz2.html

            double[,] data =
            {
                { 50,  1, 0 },
                { 70,  2, 1 },
                { 45,  3, 0 },
                { 35,  5, 0 },
                { 62,  7, 1 },
                { 50, 11, 0 },
                { 45,  4, 0 },
                { 57,  6, 0 },
                { 32,  8, 0 },
                { 57,  9, 1 },
                { 60, 10, 1 },
            };

            var regression = new ProportionalHazards(1);

            double[][] inputs = data.GetColumn(0).ToArray();
            double[]   time   = data.GetColumn(1);
            int[]      censor = data.GetColumn(2).ToInt32();


            var target = new ProportionalHazardsNewtonRaphson(regression);

            double error = target.Run(inputs, time, censor);

            // Tested against http://statpages.org/prophaz2.html
            Assert.AreEqual(0.3770, regression.Coefficients[0], 1e-4);
            Assert.AreEqual(0.2542, regression.StandardErrors[0], 1e-4);
            Assert.AreEqual(51.18181818181818, regression.Offsets[0]);

            double mean = regression.Offsets[0];

            // Baseline survivor function at predictor means
            double[] baseline =
            {
                regression.Survival(2),
                regression.Survival(7),
                regression.Survival(9),
                regression.Survival(10),
            };

            // Tested against http://statpages.org/prophaz2.html
            Assert.AreEqual(0.9979, baseline[0], 1e-4);
            Assert.AreEqual(0.9820, baseline[1], 1e-4);
            Assert.AreEqual(0.9525, baseline[2], 1e-4);
            Assert.AreEqual(0.8310, baseline[3], 1e-4);

            double[] expected =
            {
                0,                     2.51908236823927, 0.000203028311170645, 4.67823782106946E-06, 1.07100164957025,
                0.118590728553659, 0.000203028311170645,   0.0187294821517496, 1.31028937819308E-05,
                0.436716853556834, 5.14665484304978
            };

            double[] actual = new double[inputs.Length];
            for (int i = 0; i < inputs.Length; i++)
            {
                double a = actual[i] = regression.Compute(inputs[i], time[i]);
                double e = expected[i];

                Assert.AreEqual(e, a, 1e-3);
            }
            // string exStr = actual.ToString(CSharpArrayFormatProvider.InvariantCulture);
        }
        public void BaselineHazardTest()
        {
            double[,] data =
            {
                // t   c  in
                {  8, 0,  -1.2372626521865966 },
                {  4, 1,  0.22623087329625477 },
                { 12, 0,  -0.8288458543774289 },
                {  6, 0,  0.49850873850236665 },
                { 10, 0, -0.38639432341749696 },
                {  8, 1,   1.0430644689145904 },
                {  5, 0,  -1.6797141831465285 },
                {  5, 0,   1.0770992020653544 },
                {  3, 1,   1.0770992020653544 },
                { 14, 1, -0.38639432341749696 },
                {  8, 0,  -0.8969153206789568 },
                { 11, 0,   1.6897243987791061 },
                {  7, 0,  -1.2712973853373605 },
                {  7, 0, -0.38639432341749696 },
                {  7, 1, -0.45446378971902495 },
                { 12, 0,   0.4644740053516027 },
                {  8, 0,   1.4514812667237584 },
            };

            double[]          time   = data.GetColumn(0);
            SurvivalOutcome[] censor = data.GetColumn(1).To <SurvivalOutcome[]>();
            double[][]        inputs = data.GetColumn(2).ToJagged();

            var regression = new ProportionalHazards(1);

            var target = new ProportionalHazardsNewtonRaphson(regression);

            target.Normalize           = false;
            target.Lambda              = 0;
            regression.Coefficients[0] = 0.47983261821350764;

            double error = target.Run(inputs, time, censor);

            /* Tested against http://statpages.org/prophaz2.html
             *  13, 8,  0
             *  56, 4,  1
             *  25, 12, 0
             *  64, 6,  0
             *  38, 10, 0
             *  80, 8,  1
             *  0 , 5,  0
             *  81, 5,  0
             *  81, 3,  1
             *  38, 14, 1
             *  23, 8,  0
             *  99, 11, 0
             *  12, 7,  0
             *  38, 7,  0
             *  36, 7,  1
             *  63, 12, 0
             *  92, 8,  0
             */

            double[] baseline =
            {
                regression.Survival(3),  // 0.9465
                regression.Survival(4),  // 0.8919
                regression.Survival(7),  // 0.8231
                regression.Survival(8),  // 0.7436
                regression.Survival(12), // 0.7436
                regression.Survival(14), // 0.0000
            };

            Assert.AreEqual(0.9465, baseline[0], 1e-4);
            Assert.AreEqual(0.8919, baseline[1], 1e-4);
            Assert.AreEqual(0.8231, baseline[2], 1e-4);
            Assert.AreEqual(0.7436, baseline[3], 1e-4);
            Assert.AreEqual(0.7436, baseline[4], 1e-4);
            Assert.AreEqual(0.0000, baseline[5], 1e-4);

            // The value of the baseline must be exact the same if it was computed
            // after the Newton-Raphson or in a standalone EmpiricalHazard computation
            double[] outputs   = inputs.Apply(x => regression.Compute(x));
            var      empirical = EmpiricalHazardDistribution.Estimate(time, censor, outputs);

            baseline = new[]
            {
                empirical.ComplementaryDistributionFunction(3),  // 0.9465
                empirical.ComplementaryDistributionFunction(4),  // 0.8919
                empirical.ComplementaryDistributionFunction(7),  // 0.8231
                empirical.ComplementaryDistributionFunction(8),  // 0.7436
                empirical.ComplementaryDistributionFunction(12), // 0.7436
                empirical.ComplementaryDistributionFunction(14), // 0.0000
            };

            Assert.AreEqual(0.9465, baseline[0], 1e-4);
            Assert.AreEqual(0.8919, baseline[1], 1e-4);
            Assert.AreEqual(0.8231, baseline[2], 1e-4);
            Assert.AreEqual(0.7436, baseline[3], 1e-4);
            Assert.AreEqual(0.7436, baseline[4], 1e-4);
            Assert.AreEqual(0.0000, baseline[5], 1e-4);
        }