IModelling.Diff

Syntax

Diff(Input: ITimeSeries): Variant;

Parameters

Input. Variable.

Description

The Diff method calculates the increment of variable points to the previous period.

Comments

The increment of variable points is calculated by the formula: X[t]-X[t-1].

Example

Executing the example requires that the repository contains a modeling container with the MS identifier. This container includes a model with the MODEL_D identifier that is calculated by the determinate equation method and contains at least one input variable.

Add links to the Metabase and Ms system assemblies.

Sub UserProc;
Var
    Mb: IMetabase;
    ModelSpace, ModelObj: IMetabaseObject;
    Transf: IMsFormulaTransform;
    Formula: IMsFormula;
    Model: IMsModel;
    Determ: IMsDeterministicTransform;
    TransVar: IMsFormulaTransformVariable;
    Slice: IMsFormulaTransformSlice;
    TermInfo: IMsFormulaTermInfo;
    Expr: IExpression;
Begin
    Mb := MetabaseClass.Active;
    ModelSpace := Mb.ItemById("MS").Bind;
    ModelObj := Mb.ItemByIdNamespace("MODEL_D", ModelSpace.Key).Edit;
    Model := ModelObj As IMsModel;
    Transf := Model.Transform;
    Formula := Transf.FormulaItem(0);
    Determ := Formula.Method As IMsDeterministicTransform;
    TransVar := Transf.Inputs.Item(0);
    Slice := TransVar.Slices.Item(0);
    TermInfo := Transf.CreateTermInfo;
    TermInfo.Slice := Slice;
    Expr := Determ.Expression;
    Expr.References := "Ms";
    Expr.AsString := "Diff(" + TermInfo.TermInnerText + ")";
    If Expr.Valid
    Then ModelObj.Save;
    Else Debug.WriteLine("Model is not saved: error in formula");
    End If;
End Sub UserProc;

After executing the example the model will calculate the increment of the first input variable points to the previous period.

Example of Use in Expressions

Expression 1:

Diff({Brazil|BCA})

Result: the increment of Brazil|BCA time series observations is calculated to the previous period.

Use: it can be used in formulas of cross functional expression editor in any platform tool where it is available.

Expression 2:

Diff(X1)

Result: the increment of value of X1 time series points is calculated to the previous period.

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