IModelling.Hpf

Fore Syntax

Hpf(Input: ITimeSeries;
Period: IMsPeriod;
[Lambda: Integer = 100]): Variant;

Fore.NET Syntax

Hpf(Input: Prognoz.Platform.Interop.Ms.ITimeSeries;
    Period: Prognoz.Platform.Interop.Ms.IMsPeriod;
    Lambda: integer;
    Context: Prognoz.Platform.Interop.Fore.ForeRuntimeContext): object;

Parameters

Input. Smoothed variable.

Period. The period, at which method is calculated. If the parameter is set to Null, the method is calculated at the entire time period.

Lambda. The parameter controls the measure of variable smoothness.

Context. Context. The parameter is used only in Fore.NET.

Description

The Hpf method smoothes a variable using the Hodrick-Prescott filter (smoothing parameter is lambda).

Comments

Lambda.Optional parameter.The default value is 100. More the Lambda parameter value is, more "smoothed" the variable is.

The Hodrick-Prescott filter (smoothing parameter - power) is implemented by the IModelling.HpfP method.

Fore Example

Executing the example requires that the repository contains a modeling container with the MS identifier. A model with the MODEL_D identifier calculated by the method of determinate equation and containing at least one input variable must be available in this container.

Add links to the Metabase, Ms system assemblies.

Sub UserHpf;
Var
    Mb: IMetabase;
    ModelSpace, ModelObj: IMetabaseObject;
    Transf: IMsFormulaTransform;
    Formula: IMsFormula;
    Model: IMsModel;
    Determ: IMsDeterministicTransform;
    TransVar: IMsFormulaTransformVariable;
    Slice: IMsFormulaTransformSlice;
    TermInfo: IMsFormulaTermInfo;
    Expr: IExpression;
Begin
    // Get repository
    Mb := MetabaseClass.Active;
    // Get modeling container
    ModelSpace := Mb.ItemById("MS").Bind;
    // Get model
    ModelObj := Mb.ItemByIdNamespace("MODEL_D", ModelSpace.Key).Edit;
    Model := ModelObj As IMsModel;
    // Get model calculation parameters
    Transf := Model.Transform;
    Formula := Transf.FormulaItem(0);
    Determ := Formula.Method As IMsDeterministicTransform;
    // Get the first input variable
    TransVar := Transf.Inputs.Item(0);
    Slice := TransVar.Slices.Item(0);
    TermInfo := Transf.CreateTermInfo;
    TermInfo.Slice := Slice;
    // Set mode of passing variable into calculation
    TermInfo.Type := MsFormulaTermType.Pointwise;
    // Get model calculation expression
    Expr := Determ.Expression;
    Expr.References := "Ms";
    // Set model calculation expression
    Expr.AsString := "Hpf(" + TermInfo.TermInnerText + ", SetPeriod(" +
        """" + "01.01.2000" + """" + "," + """" + "01.01.2015" + """" + "), 120)";
    // Check if the expression is correct
    If Expr.Valid
        // If the expression is set correctly, save the model
        Then ModelObj.Save;
        // If the expression is incorrect, display a message to the console window
        Else Debug.WriteLine("Model is not saved: error in the formula");
    End If;
End Sub UserHpf;

After executing the example the model smoothes data of the first input variable with the Hodrick-Prescott filter from 2000 to 2015.

Fore.NET Example

The requirements and result of the Fore.NET example execution match with those in the Fore example.

Imports Prognoz.Platform.Interop.Ms;
Imports Prognoz.Platform.Interop.ForeSystem;
…
Public Shared Sub Main(Params: StartParams);
Var
    Mb: IMetabase;
    ModelSpace, ModelObj: IMetabaseObject;
    Transf: IMsFormulaTransform;
    Formula: IMsFormula;
    Model: IMsModel;
    Determ: IMsDeterministicTransform;
    TransVar: IMsFormulaTransformVariable;
    Slice: IMsFormulaTransformSlice;
    TermInfo: IMsFormulaTermInfo;
    Expr: IExpression;
Begin
    // Get repository
    Mb := Params.Metabase;
    // Get modeling container
    ModelSpace := Mb.ItemById["MS"].Bind();
    // Get model
    ModelObj := Mb.ItemByIdNamespace["MODEL_D", ModelSpace.Key].Edit();
    Model := ModelObj As IMsModel;
    // Get model calculation parameters
    Transf := Model.Transform;
    Formula := Transf.FormulaItem[0];
    Determ := Formula.Method As IMsDeterministicTransform;
    // Get the first input variable
    TransVar := Transf.Inputs.Item[0];
    Slice := TransVar.Slices.Item[0];
    TermInfo := Transf.CreateTermInfo();
    TermInfo.Slice := Slice;
    // Set mode of passing variable into calculation
    TermInfo.Type := MsFormulaTermType.mfttPointwise;
    // Get model calculation expression
    Expr := Determ.Expression;
    Expr.References := "Ms";
    // Set model calculation expression
    Expr.AsString := "Hpf(" + TermInfo.TermInnerText + ", SetPeriod(" +
        """" + "01.01.2000" + """" + "," + """" + "01.01.2015" + """" + "), 120)";
    // Check if the expression is correct
    If Expr.Valid
        // If the expression is set correctly, save the model
        Then ModelObj.Save();
        // If the expression is incorrect, display a message to the console window
        Else System.Diagnostics.Debug.WriteLine("Model is not saved: error in the formula");
    End If;
End Sub;

Example of Use in Expressions

Expression 1:

Hpf({Chicago - population[t]}, Null, 130)

Result: data of the Chicago - population[t] time series is smoothed with the Hodrick-Prescott filter at the entire data period. Smoothing parameter equals to 130.

Use: it can be used in formulas of calculated series of time series database and in formulas of attribute-based models of modeling container.

Expression 2:

Hpf(X1, setperiod("01.01.2000", "01.01.2015"))

Result: data of the X1 factor is smoothed with the Hodrick-Prescott filter at the specified data period.

Use: it can be used in model variable-based formulas of modeling container.