Variance(Parameters: Array): Variant;
Variance(Context: Prognoz.Platform.Interop.Fore.ForeRuntimeContext; Parameters: System.Array): object;
Context. Context. The parameter is used only in Fore.NET.
Parameters. Variable.
The Variance method returns variance of the variable.
If more than one variable is specified in Parameters, variance for corresponding variable points is calculated. For example, variance for points of 2018 by all variables.
Variables in Parameters must be separated via comma.
A calculated period can be set for the method. To do this, use the IModelling.SetPeriod method, by specifying it at any place of input array.
To calculate the method without taking into account empty values, use the IgnoreMissing parameter by specifying it in any place of the input array. Available values of the parameter:
True. Default value. Calculation does not take into account empty values.
False. Calculation takes into account empty values.
Executing the example requires that the repository contains a modeling container with the MS identifier. This contains includes a model with the MODEL_D identifier that is calculated by the determinate equation method and contains 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;
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;
After executing the example the model calculates values of the second input variable increased by variance of the first input variable.
Expression 1:
Variance({Brazil|BCA}, False, SetPeriod(2000,2010))
Result: Brazil|BCA series variance is calculated taking into account empty values 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: X1 factor variance 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.
Application: it can be used in any expressions.
See also:
IModelling | Variance | Time Series Database: Calculator | Modeling Container: Editing Regressor or Formula