Order a selctionset by property?

[Tuoni]

Does anybody know if it's possible to order a selectionset by a specified property in VBA?

What I am trying to do:

I have a collection of polylines on a drawing, all of which are contained in a selection set. I then want to iterate through the selection set, starting with the polyline with the smallest area through to the polyline with the largest area.

Does anybody know of any way to do this?

[dbroada]

I would probably put their values in an array and sort on that.
Or a sorted list box?

in the meantime I'd ask here and hope somebody comes up with a sensible answer.

[Tuoni]

Thanks for your quick response, I am trying to avoid doing that
as I need several properties on each of the objects - for instance, layer name, area, perimeter/length...

I was wondering if there was a more efficient way?

[dbroada]

As I was typing that I thought "I bet he doesn't want to do this". But having typed I wasn't going to not post!

However, having now checked the help it doesn't look like there is a method available.

I would still be inclined to do an array. You only have to store an order, not the objects. Something like....

if object(order(i)).area < object(order(i+1)).area
then temp = order(i)
order(i) = order(i+1)
order(i+1) = temp

to get an array of order. Then step through by

mySelectionSet.item(order(i))

(totally off the top of my head so probably not practical)

[Tuoni]

I have checked the help and have searched on other forums (such as the AutoDesk discussion forum) but also to no avail, that's why I aired it here.

You should know, as well as I (if not better), that VBA is a very impractical language in AutoCAD due to its... "quirks"... shall we say?

Still, storing (potentially) hundreds of polylines in a selection set, then having to manually trawl through it to find increasing areas is a complete ballache and isn't going to help the execution time of the software

Thanks for your responses anyway, I think I will end up having to do it this way if you have any other thoughts in the meantime, I'd be grateful

[dbroada]

I find VBA easier than LISP. But it is frustrating, especially when that one command that would have saved you SO MUCH TIME isn't on the drop down list but does work if you were just brave enough to try it.

I agree, storing hundreds of items in an array and manipulating them isn't ideal. I do sometimes resort to writing my own custom control in VB at times but I can only get them to work on my machine. No matter how closly I follow insructions I just can't seem to get them to work reliably on other machines. (not that I can see a use here)

[Tuoni]

I find VBA easier than LISP. But it is frustrating, especially when that one command that would have saved you SO MUCH TIME isn't on the drop down list but does work if you were just brave enough to try it.

I haven't ever learnt LISP, I must admit (though from doing reading round it seems that VBA is more suited to my task anyway... using ADO and integrating with mirco$0ft office applications etc) but most of my software in recent years has been in languages without drop down lists so I have lost reliance on them - drop down lists being an invention of the devil is shown by the fact that "area" is not on the list for an entity (yes, I understand that it is only applicable in certain cases, but surely the programmer should know what sort of entity is being passed to the function?)

Also, from my experience, a lot of VBA seems to be somewhat of a "Dark Art", there is little true documentation on a lot of the features - which is exactly why I joined usergroups lol

anyways </rant>

I'll keep digging and thinking. Got a few hour's train journey back home yet... I might as well chew it over rather than just purely staring blankly out of the window )

[SEANT]

The Collection object may be a good alternative to a dynamic array. It doesn't require "redim"ming , and adding items at a specific spot if a relatively easy task.

Option Explicit

Sub SortByArea()
Dim intCode(0) As Integer
Dim varData(0) As Variant
Dim entLWP As AcadLWPolyline
Dim entLWPSorted As AcadLWPolyline
Dim colSmall2Large As New Collection
Dim intSSCount As Integer
Dim i As Integer
Dim j As Integer
Dim colSS As AcadSelectionSet
      intCode(0) = 0: varData(0) = "LWPOLYLINE"
      intSSCount = SoSSS(intCode, varData) 'create selection
      Set colSS = ThisDrawing.SelectionSets.Item("TempSSet") 
      If intSSCount > 0 Then
         Set entLWP = colSS.Item(0)
         colSmall2Large.Add entLWP 'add first item as baseline
         For i = 1 To intSSCount - 1
            Set entLWP = colSS.Item(i)
            For j = 1 To colSmall2Large.Count
               If entLWP.Area <= colSmall2Large.Item(j).Area Then
                  colSmall2Large.Add entLWP, , j
                  Exit For
               ElseIf j = colSmall2Large.Count Then
                  colSmall2Large.Add entLWP, , , j 'current Pline has largest area
               End If
            Next
         Next
      End If
      For Each entLWP In colSmall2Large
         MsgBox "Area: " & entLWP.Area & vbCr & "Perimeter: " & entLWP.Length & vbCr & "Layer: " & entLWP.Layer
      Next
      Set colSS = Nothing
      Set entLWP = Nothing
End Sub

'''''''Generic Selection Set creation routine '''''''

Function SoSSS(Optional grpCode As Variant, Optional dataVal As Variant) As Integer
   Dim TempObjSS As AcadSelectionSet
   SSClear 'make sure SS doesn't already exist
   Set TempObjSS = ThisDrawing.SelectionSets.Add("TempSSet")
         'Select on Screen Selection Set
   If IsMissing(grpCode) Then
      TempObjSS.SelectOnScreen
   Else
      TempObjSS.SelectOnScreen grpCode, dataVal
   End If
   SoSSS = TempObjSS.Count
   Set TempObjSS = Nothing
End Function

Private Sub SSClear()
Dim SSS As AcadSelectionSets
   On Error Resume Next
   Set SSS = ThisDrawing.SelectionSets
      If SSS.Count > 0 Then
         SSS.Item("TempSSet").Delete
      End If
      Set SSS = Nothing
End Sub

[Tuoni]

Thankyou both for your quick responses, and thanks SEANT, that code does exactly what I wanted, and on my "test" drawing, it runs quickly enough for me (I was quite worried at the prospect of sorting an array - not a quick process at the best of times >.<).

Thanks again

(Oh, and just so as you know... I did just stare blankly out of the window on the train last night hehe)

[SEANT]

I hope the passing scenery, blankly stared upon, was nice.