Set different value to a set of elements

[Anonymous]

Hi everyone,

So I am trying to filter all the beams in my project and set values to the Parameter Mark. I would like to mark it in a sequence, say from 3 to 10. Here are what I have done so far:

from Autodesk.Revit.DB import *

doc = __revit__.ActiveUIDocument.Document

bc = FilteredElementCollector(doc).OfCategory(BuiltInCategory.OST_StructuralFraming).WhereElementIsNotElementType().ToElements()

t = Transaction(doc, 'Mark changing')

t.Start()

for bm in bc:
	mark = bm.LookupParameter("Mark")
	if mark:
		for i in range(3,10):
			newMark = mark.Set(str(i))

t.Commit()

I have 7 beams and if this code works, it should give them the Mark value of 3, 4, 5, 6, 7, 8, 9, respectively. However, my code only give all beams one value of 9. I would appreciate any help.

Cheers

Thai

[naveen.kumar.t · Accepted solution]

Try this code

 Dim i As Integer = 3
            Dim collector As FilteredElementCollector = New FilteredElementCollector(doc).OfCategory(BuiltInCategory.OST_StructuralFraming).WhereElementIsNotElementType()
            Dim eids As IList(Of ElementId) = TryCast(collector.ToElementIds(), IList(Of ElementId))
            TaskDialog.Show("BEams count", eids.Count.ToString())
            For Each eid As ElementId In eids
                Dim e As Element = doc.GetElement(eid)
                Dim P As Parameter = e.LookupParameter("Mark")
                If P IsNot Nothing Then
                    P.[Set](i.ToString())
                    If Not P.HasValue Then
                        P.SetValueString(i.ToString())
                    End If

                    i = i + 1
                End If
            Next

            doc.Regenerate()

[jeremy_tammik · Accepted solution]

Many thanks to Naveen for answering!

In the original code, you loop from 3 to 9 for each of the beams, set each of those values to the parameter in each of the beams, and end up at the value 9 on each one of them. That explains the behaviour you describe.

You can solve it by not looping over all the numbers in an inner loop, but just incrementing the mark number after setting each element's parameter in turn.

Some comments and suggestions to both of you:

• Using `ToElements` is often not required and adds a performance hit: http://thebuildingcoder.typepad.com/blog/2012/09/findelement-and-collector-optimisation.html
• LookupParameter is not optimal; when possible, use a built-in parameter enum instead of the display name.
• The `ToElementIds` cast is also unnecessary and wastes time and memory.
• The cast to IList is also unnecessary and wastes time and memory.
• No need to use both Set and SetValueString.
• I generally try to avoid using `SetValueString`: http://thebuildingcoder.typepad.com/blog/2018/04/revit-20183-setvaluestring-and-external-events.html...
• No need to regenerate if the transaction is committed right afterwards.

Here is my suggestion how to solve this, iterating directly over the collector with no casts at all:

    void NumberStructuralFraming( Document doc )
    {
      FilteredElementCollector beams
        = new FilteredElementCollector( doc )
          .OfCategory( BuiltInCategory.OST_StructuralFraming )
          .WhereElementIsNotElementType();

      using( Transaction t = new Transaction( doc ) )
      {
        t.Start( "Renumber marks" );

        int mark_number = 3;

        foreach( FamilyInstance beam in beams )
        {
          Parameter p = beam.get_Parameter(
            BuiltInParameter.ALL_MODEL_MARK );

          p.Set( (mark_number++).ToString() );
        }
        t.Commit();
      }
    }

I hope this helps.

Cheers,

Jeremy

[jeremy_tammik · Accepted solution]

By the way, I once implemented a more full-fledged element numbering system for structural concrete setout points:

http://thebuildingcoder.typepad.com/blog/2012/08/structural-concrete-setout-point-add-in.html

https://github.com/jeremytammik/SetoutPoints

Cheers,

Jeremy

[Anonymous]

Thank you all for suggesting and commenting. I have combined your ideas and have come up with a simple solution as following:

from Autodesk.Revit.DB import *

doc = __revit__.ActiveUIDocument.Document

bc = FilteredElementCollector(doc).OfCategory(BuiltInCategory.OST_StructuralFraming).WhereElementIsNotElementType()
	
t = Transaction(doc, 'Mark changing')

t.Start()
i = 1
for bm in bc:
	mark = bm.LookupParameter("Mark")
	newMark = mark.Set(str(i))
	i = i+1

t.Commit()

However, I still do not get Jeremy's suggestion: 

• "LookupParameter is not optimal; when possible, use a built-in parameter enum instead of the display name."

[jeremy_tammik]

Well done!

Looking good.

Still room for improvement:

A transaction should be enclosed in a `using` statement: 

http://thebuildingcoder.typepad.com/blog/2012/04/using-using-automagically-disposes-and-rolls-back.h...

LookupParameter takes a language dependent display string.

This has several disadvantages:

• Several parameters can have the same display string. How do you guarantee you got the right one?
• Display strings are language dependent. How are you going to go international?
• String comparisons are more expensive than integer or enum value comparisons. Are you interested in speed? Perfection?

Cheers,

Jeremy

[Anonymous]

Thank you for your suggestions Jeremy. I will dig deeper about this matter.

Regards,

Thai