StDv(Parameters: Array): Variant;
StDv(Context: Prognoz.Platform.Interop.Fore.ForeRuntimeContext; Parameters: System.Array): object;
Context. Context. The parameter is used only in Fore.NET.
Parameters. Variable.
The StDv method returns the standard deviation for the specified variable.
If more than one variable is specified in Parameters, standard deviation of corresponding variable points is calculated. For example, standard deviation of 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 + "+StDv(" + 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 + "+StDv(" + 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 standard deviation of the first input variable.
Expression 1:
StDv({Brazil|BCA})
Result: standard deviation of observations of the Brazil|BCA series is calculated.
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:
StDv(X1, X2, False, SetPeriod(2000,2010))
Result: standard deviation of corresponding points of the X1 and X2 factors is calculated taking into account empty values from 2000 to 2010.
Use: it can be used in model variable-based formulas of modeling container.
Expression 3:
StDv(1,2,3.5,4,5)
Result: 1,6.
Application: it can be used in any expressions.
See also:
IModelling | Standard Deviation | Time Series Database: Calculator | Modeling Container: Editing Regressor or Formula