Sorting VBS Arrays with .NET

This guide demonstrates how to use the .NET Framework to sort arrays in RhinoScript.

Overview

One of the big limitations in VBScript is that there is no easy way to sort a list of items. To put a list in alphabetical order requires you to either use the pre-canned RhinoScript methods, such as SortNumbers, SortPoints or SortStrings, or write a sorting function of your own, like the following bubble sort code:

For i = (UBound(arrNames) - 1) to 0 Step -1
  For j= 0 to i
    If UCase(arrNames(j)) >
      UCase(arrNames(j+1)) Then
        strHolder = arrNames(j+1)
        arrNames(j+1) = arrNames(j)
        arrNames(j) = strHolder
    End If
  Next
Next

Discussion

There is another option and that is to use the .NET Framework to help. The majority of .NET Framework classes are unusable in VBScript. However, there are a large number of .NET classes that have COM-callable wrappers. T his means these classes include a COM interface enabling them to be accessed from VBScript.

For example, consider the following script:

Set DataList = CreateObject("System.Collections.ArrayList")
DataList.Add "B"
DataList.Add "C"
DataList.Add "E"
DataList.Add "D"
DataList.Add "A"
DataList.Sort()
For Each strItem in DataList
  Rhino.Print strItem
Next

Notice that we have created an instance of the .NET Framework class System.Collections.ArrayList. We then use the Add method to add five items to the list. To sort the list, all we need to do is call the ArrayList’s Sort method.

Now, what if you really wanted those values in descending order? In this case, just call ArrayList’s Sort method after calling the Sort method.

Set DataList = CreateObject("System.Collections.ArrayList")
DataList.Add "B"
DataList.Add "C"
DataList.Add "E"
DataList.Add "D"
DataList.Add "A"
DataList.Sort()
DataList.Reverse()
For Each strItem in DataList
  Rhino.Print strItem
Next

Also, have you ever tried to remove an item from a VBScript array? It is not easy. But, with the .NET Framework’s ArrayList, you just need to call the Remove method. The following script, an ArrayList, sorts it, and then removes the entry for D

Set DataList = CreateObject("System.Collections.ArrayList")
DataList.Add "B"
DataList.Add "C"
DataList.Add "E"
DataList.Add "D"
DataList.Add "A"
DataList.Sort()
DataList.Remove("D")
For Each strItem in DataList
  Rhino.Print strItem
Next

Copying items VBScript arrays and an ArrayList is just as easy. In the following script, an ArrayList is used to sort a list of layer names…

LayerNames = Rhino.LayerNames
Set DataList = CreateObject("System.Collections.ArrayList")
For i = 0 To UBound(LayerNames)
  DataList.Add LayerNames(i)
Next
DataList.Sort()
For i = 0 To UBound(LayerNames)
  LayerNames(i) = DataList(i)
Next
Layer = Rhino.ListBox(LayerNames, "Layer to set current")