/// <summary>
        /// Predict a target using a linear regression model trained with the SDCA trainer.
        /// </summary>
        /// <param name="catalog">The regression catalog trainer object.</param>
        /// <param name="label">The label, or dependent variable.</param>
        /// <param name="features">The features, or independent variables.</param>
        /// <param name="weights">The optional example weights.</param>
        /// <param name="options">Advanced arguments to the algorithm.</param>
        /// <param name="onFit">A delegate that is called every time the
        /// <see cref="Estimator{TInShape, TShape, TTransformer}.Fit(DataView{TInShape})"/> method is called on the
        /// <see cref="Estimator{TInShape, TOutShape, TTransformer}"/> instance created out of this. This delegate will receive
        /// the linear model that was trained.  Note that this action cannot change the result in any way; it is only a way for the caller to
        /// be informed about what was learnt.</param>
        /// <returns>The predicted output.</returns>
        /// <example>
        /// <format type="text/markdown">
        /// <![CDATA[
        ///  [!code-csharp[SDCA](~/../docs/samples/docs/samples/Microsoft.ML.Samples/Static/SDCARegression.cs)]
        /// ]]></format>
        /// </example>
        public static Scalar <float> Sdca(this RegressionCatalog.RegressionTrainers catalog,
                                          Scalar <float> label, Vector <float> features, Scalar <float> weights,
                                          SdcaRegressionTrainer.Options options,
                                          Action <LinearRegressionModelParameters> onFit = null)
        {
            Contracts.CheckValue(label, nameof(label));
            Contracts.CheckValue(features, nameof(features));
            Contracts.CheckValueOrNull(weights);
            Contracts.CheckValueOrNull(options);
            Contracts.CheckValueOrNull(onFit);

            var rec = new TrainerEstimatorReconciler.Regression(
                (env, labelName, featuresName, weightsName) =>
            {
                options.LabelColumnName   = labelName;
                options.FeatureColumnName = featuresName;

                var trainer = new SdcaRegressionTrainer(env, options);
                if (onFit != null)
                {
                    return(trainer.WithOnFitDelegate(trans => onFit(trans.Model)));
                }
                return(trainer);
            }, label, features, weights);

            return(rec.Score);
        }
        /// <summary>
        /// Predict a target using a linear regression model trained with the SDCA trainer.
        /// </summary>
        /// <param name="ctx">The regression context trainer object.</param>
        /// <param name="label">The label, or dependent variable.</param>
        /// <param name="features">The features, or independent variables.</param>
        /// <param name="weights">The optional example weights.</param>
        /// <param name="l2Const">The L2 regularization hyperparameter.</param>
        /// <param name="l1Threshold">The L1 regularization hyperparameter. Higher values will tend to lead to more sparse model.</param>
        /// <param name="maxIterations">The maximum number of passes to perform over the data.</param>
        /// <param name="loss">The custom loss, if unspecified will be <see cref="SquaredLoss"/>.</param>
        /// <param name="advancedSettings">A delegate to set more settings.
        /// The settings here will override the ones provided in the direct method signature,
        /// if both are present and have different values.
        /// The columns names, however need to be provided directly, not through the <paramref name="advancedSettings"/>.</param>
        /// <param name="onFit">A delegate that is called every time the
        /// <see cref="Estimator{TInShape, TShape, TTransformer}.Fit(DataView{TInShape})"/> method is called on the
        /// <see cref="Estimator{TInShape, TOutShape, TTransformer}"/> instance created out of this. This delegate will receive
        /// the linear model that was trained.  Note that this action cannot change the result in any way; it is only a way for the caller to
        /// be informed about what was learnt.</param>
        /// <returns>The predicted output.</returns>
        /// <example>
        /// <format type="text/markdown">
        /// <![CDATA[
        ///  [!code-csharp[SDCA](~/../docs/samples/docs/samples/Microsoft.ML.Samples/Static/SDCARegression.cs)]
        /// ]]></format>
        /// </example>
        public static Scalar <float> Sdca(this RegressionContext.RegressionTrainers ctx,
                                          Scalar <float> label, Vector <float> features, Scalar <float> weights = null,
                                          float?l2Const     = null,
                                          float?l1Threshold = null,
                                          int?maxIterations = null,
                                          ISupportSdcaRegressionLoss loss = null,
                                          Action <SdcaRegressionTrainer.Arguments> advancedSettings = null,
                                          Action <LinearRegressionModelParameters> onFit            = null)
        {
            Contracts.CheckValue(label, nameof(label));
            Contracts.CheckValue(features, nameof(features));
            Contracts.CheckValueOrNull(weights);
            Contracts.CheckParam(!(l2Const < 0), nameof(l2Const), "Must not be negative, if specified.");
            Contracts.CheckParam(!(l1Threshold < 0), nameof(l1Threshold), "Must not be negative, if specified.");
            Contracts.CheckParam(!(maxIterations < 1), nameof(maxIterations), "Must be positive if specified");
            Contracts.CheckValueOrNull(loss);
            Contracts.CheckValueOrNull(advancedSettings);
            Contracts.CheckValueOrNull(onFit);

            var rec = new TrainerEstimatorReconciler.Regression(
                (env, labelName, featuresName, weightsName) =>
            {
                var trainer = new SdcaRegressionTrainer(env, labelName, featuresName, weightsName, loss, l2Const, l1Threshold, maxIterations, advancedSettings);
                if (onFit != null)
                {
                    return(trainer.WithOnFitDelegate(trans => onFit(trans.Model)));
                }
                return(trainer);
            }, label, features, weights);

            return(rec.Score);
        }
        /// <summary>
        /// Predict a target using a linear regression model trained with the SDCA trainer.
        /// </summary>
        /// <param name="catalog">The regression catalog trainer object.</param>
        /// <param name="label">The label, or dependent variable.</param>
        /// <param name="features">The features, or independent variables.</param>
        /// <param name="weights">The optional example weights.</param>
        /// <param name="l2Regularization">The L2 regularization hyperparameter.</param>
        /// <param name="l1Threshold">The L1 regularization hyperparameter. Higher values will tend to lead to more sparse model.</param>
        /// <param name="numberOfIterations">The maximum number of passes to perform over the data.</param>
        /// <param name="lossFunction">The custom loss, if unspecified will be <see cref="SquaredLoss"/>.</param>
        /// <param name="onFit">A delegate that is called every time the
        /// <see cref="Estimator{TInShape, TShape, TTransformer}.Fit(DataView{TInShape})"/> method is called on the
        /// <see cref="Estimator{TInShape, TOutShape, TTransformer}"/> instance created out of this. This delegate will receive
        /// the linear model that was trained.  Note that this action cannot change the result in any way; it is only a way for the caller to
        /// be informed about what was learnt.</param>
        /// <returns>The predicted output.</returns>
        /// <example>
        /// <format type="text/markdown">
        /// <![CDATA[
        ///  [!code-csharp[SDCA](~/../docs/samples/docs/samples/Microsoft.ML.Samples/Static/SDCARegression.cs)]
        /// ]]></format>
        /// </example>
        public static Scalar <float> Sdca(this RegressionCatalog.RegressionTrainers catalog,
                                          Scalar <float> label, Vector <float> features, Scalar <float> weights = null,
                                          float?l2Regularization = null,
                                          float?l1Threshold      = null,
                                          int?numberOfIterations = null,
                                          ISupportSdcaRegressionLoss lossFunction        = null,
                                          Action <LinearRegressionModelParameters> onFit = null)
        {
            Contracts.CheckValue(label, nameof(label));
            Contracts.CheckValue(features, nameof(features));
            Contracts.CheckValueOrNull(weights);
            Contracts.CheckParam(!(l2Regularization < 0), nameof(l2Regularization), "Must not be negative, if specified.");
            Contracts.CheckParam(!(l1Threshold < 0), nameof(l1Threshold), "Must not be negative, if specified.");
            Contracts.CheckParam(!(numberOfIterations < 1), nameof(numberOfIterations), "Must be positive if specified");
            Contracts.CheckValueOrNull(lossFunction);
            Contracts.CheckValueOrNull(onFit);

            var rec = new TrainerEstimatorReconciler.Regression(
                (env, labelName, featuresName, weightsName) =>
            {
                var trainer = new SdcaRegressionTrainer(env, labelName, featuresName, weightsName, lossFunction, l2Regularization, l1Threshold, numberOfIterations);
                if (onFit != null)
                {
                    return(trainer.WithOnFitDelegate(trans => onFit(trans.Model)));
                }
                return(trainer);
            }, label, features, weights);

            return(rec.Score);
        }