Variance(Inputs: Array): Variant;
Variance(Context: Prognoz.Platform.Interop.Fore.ForeRuntimeContext; Inputs: System.Array): object;
Context. Context. The parameter is used only in Fore.NET.
Inputs. Variable.
The Variance method returns variance of the variable.
The method provides a possibility to set calculation period. To do this, use the IModelling.SetPeriod method, by specifying it at any place of input array.
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 method of determinate equation and containing more than one input variable.
Add links to the Metabase, 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;
Inp_1: String;
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;
TermInfo.Type := MsFormulaTermType.Serie;
Inp_1 := TermInfo.TermInnerText;
TransVar := Transf.Inputs.Item(1);
Slice := TransVar.Slices.Item(0);
TermInfo := Transf.CreateTermInfo;
TermInfo.Slice := Slice;
TermInfo.Type := MsFormulaTermType.Pointwise;
Expr := Determ.Expression;
Expr.References := "Ms";
Expr.AsString := TermInfo.TermInnerText + "+Variance(" + Inp_1 + ")";
If Expr.Valid
Then ModelObj.Save;
Else Debug.WriteLine("The model is not saved: error in formula");
End If;
End Sub UserProc;
After executing the example, the model calculates values of the second input variable increased by variance of the first input variable.
The requirements and result of the Fore.NET example execution match with those in the Fore example.
Imports Prognoz.Platform.Interop.ForeSystem;
Imports Prognoz.Platform.Interop.Ms;
…
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;
Inp_1: String;
Expr: IExpression;
Begin
Mb := Params.Metabase;
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;
TermInfo.Type := MsFormulaTermType.mfttSerie;
Inp_1 := TermInfo.TermInnerText;
TransVar := Transf.Inputs.Item[1];
Slice := TransVar.Slices.Item[0];
TermInfo := Transf.CreateTermInfo();
TermInfo.Slice := Slice;
TermInfo.Type := MsFormulaTermType.mfttPointwise;
Expr := Determ.Expression;
Expr.References := "Ms";
Expr.AsString := TermInfo.TermInnerText + "+Variance(" + Inp_1 + ")";
If Expr.Valid
Then ModelObj.Save();
Else System.Diagnostics.Debug.WriteLine("Model is not saved: error in formula");
End If;
End Sub;
Expression 1:
Variance({Brazil|BCA}, SetPeriod(2000,2010))
Result: variance of the Brazil|BCA series is calculated for the period from 2000 to 2010.
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:
Variance(X1)
Result: the variance of the X1 factor is calculated.
Use: it can be used in model variable-based formulas of modeling container.
Expression 3:
Variance(1, 2, 3, 4)
Result: 1,67.
Use: it can be used in formulas of calculated series of time series database and modeling container models.
See also:
IModelling | Variance | Time Series Database: Calculator | Modeling Container: Editing Regressor or Formula