VB Apply Transform Example

Imports System

Imports CenterSpace.NMath.Core


Namespace CenterSpace.NMath.Examples.VisualBasic

  A .NET example in Visual Basic showing how to use the Apply and Transform methods on 
  a DataFrame and its columns.
  Module ApplyTransformExample

    Sub Main()

      Dim Data As DataFrame = New DataFrame()
      Data.AddColumn(New DFStringColumn("first"))
      Data.AddColumn(New DFStringColumn("last"))
      Data.AddColumn(New DFDateTimeColumn("birthdate"))
      Data.AddColumn(New DFNumericColumn("test1"))
      Data.AddColumn(New DFNumericColumn("test2"))
      Data = InitializeData(Data)

      Console.WriteLine()
      Console.WriteLine()
      Console.WriteLine("Original data...")
      Console.WriteLine()
      Console.WriteLine(Data)

      Combine first name and last name columns into a new 
      column and then add it to the data frame.
      Dim Concatenate As New Func(Of String, String, String)(AddressOf CombineNames)
      Dim FullNames As DFStringColumn = (CType(Data("first"), DFStringColumn).Apply("full names", Concatenate, CType(Data("last"), DFStringColumn)))
      Data.InsertColumn(0, FullNames)

      Remove first name, last name columns
      Data.RemoveColumn("first")
      Data.RemoveColumn("last")

      Console.WriteLine()
      Console.WriteLine("Concatenate first and last names...")
      Console.WriteLine()
      Console.WriteLine(Data)

      Scale all test2 scores up by 10 points
      CType(Data("test2"), DFNumericColumn).Transform(New Func(Of Double, Double)(AddressOf Scale))

      Console.WriteLine()
      Console.WriteLine("Scale test2 up by 10%...")
      Console.WriteLine()
      Console.WriteLine(Data)

      Cap all grades at 95
      CType(Data("test1"), DFNumericColumn).Transform(New Func(Of Double, Double)(AddressOf Cap))
      CType(Data("test2"), DFNumericColumn).Transform(New Func(Of Double, Double)(AddressOf Cap))

      Console.WriteLine()
      Console.WriteLine("Cap grades at 95%...")
      Console.WriteLine()
      Console.WriteLine(Data)

      Add a new column which is the weighted average of the two tests
      Dim WeightedFunction As New Func(Of Double, Double, Double)(AddressOf Weighted)
      Dim Test1 As DFNumericColumn = CType(Data("test1"), DFNumericColumn)
      Dim Test2 As DFNumericColumn = CType(Data("test2"), DFNumericColumn)
      Dim Final As DFNumericColumn = CType(Test1.Apply("final", WeightedFunction, Test2), DFNumericColumn)
      Data.AddColumn(Final)

      Console.WriteLine()
      Console.WriteLine("Final weighted average...")
      Console.WriteLine()
      Console.WriteLine(Data)

      Round all numeric values to the nearest whole number
      CType(Data("test1"), DFNumericColumn).Transform(New Func(Of Double, Integer, Double)(AddressOf Math.Round), 1)
      CType(Data("test1"), DFNumericColumn).NumericFormat = "F1"

      CType(Data("test2"), DFNumericColumn).Transform(New Func(Of Double, Integer, Double)(AddressOf Math.Round), 1)
      CType(Data("test2"), DFNumericColumn).NumericFormat = "F1"

      CType(Data("final"), DFNumericColumn).Transform(New Func(Of Double, Integer, Double)(AddressOf Math.Round), 1)
      CType(Data("final"), DFNumericColumn).NumericFormat = "F1"

      Console.WriteLine()
      Console.WriteLine("Round to one decimal place...")
      Console.WriteLine()
      Console.WriteLine(Data)

      Console.WriteLine()
      Console.WriteLine("Press Enter Key")
      Console.Read()
    End Sub

    Function InitializeData(ByRef Data As DataFrame) As DataFrame
      Data.AddRow(1, "Jack", "Cooper", "1/29/1968", 55.4, 63.3)
      Data.AddRow(2, "Henri", "Robert", "12/4/1978", 85.6, 90.2)
      Data.AddRow(3, "Sasha", "Klein", "5/7/1947", 65.4, 64.3)
      Data.AddRow(4, "Gail", "Blake", "8/4/1985", 75.1, 48.2)
      Data.AddRow(5, "Paul", "Norton", "9/21/1981", 55.4, 62.3)
      Data.AddRow(6, "Harry", "Liu", "10/12/1972", 85.6, 87.3)
      Data.AddRow(7, "Roberto", "Ortiz", "11/3/1978", 59.2, 93.3)
      Data.AddRow(8, "Marie", "Flint", "4/5/1972", 66.7, 38.2)
      Return Data
    End Function

    Function CombineNames(ByVal First As String, ByVal Last As String) As String
      Return First + " " + Last
    End Function

    Function Scale(ByVal Score As Double) As Double
      Return Score + 10.0
    End Function

    Function Cap(ByVal Score As Double) As Double
      If Score > 95.0 Then
        Return 95.0
      Else
        Return Score
      End If
    End Function

    Function Weighted(ByVal Test1 As Double, ByVal Test2 As Double) As Double
      Return (0.4 * Test1) + (0.6 * Test2)
    End Function

  End Module

End Namespace