Writing ArcMap Label Expression in VBscript?

Question

I have to columns, pipe material and pipe size, I only want to label pipes with a size greater than 2"

I am trying to do this but keeps kicking back and error, can anyone assist in what im doing wrong?

Function FindLabel ( [PIPE_MATERIAL] , [PIPE_INTERNAL_DIAMETER] )
  if ( [PIPE_INTERNAL_DIAMETER] > 2") then
   FindLabel = [PIPE_MATERIAL] 
  end if
End Function

Answer 1

Function FindLabel ( [PIPE_MATL], [PIPE_DIA] )
 ' this just pulls first digit from PIPE_DIA string 2", 3" & converts to Double type - you may have to play around with...  
   If CDbl( Mid([PIPE_DIA], 1, Len([PIPE_DIA])-1)) > 2 then
      FindLabel = [PIPE_MATL]
   else 
      FindLabel = ""
   end if
End Function

Adding unit decorations to a data field (like inch marks etc.) is always a BAD idea, poor database structure. The reason your code fails is your mixing data types in your "If" statement. You need to compare either 'all string' or 'all number' types.

Answer 2

I think it must be near your 'if ( [PIPE_INTERNAL_DIAMETER] > 2") then' line.

Your wanting to perform a logical mathematical operation there and the double quote after the 2" is probably getting in the way - getting interpreted as a string.

if PIPE_INTERNAL_DIAMETER is an integer field then you need to do something like:

Function FindLabel ( [PIPE_MATL], [P_INT_DIAM] )
if ( [P_INT_DIAM] > 2) then
  FindLabel = [PIPE_MATL]
end if
End Function

Answer 3

I'm not really good with VB, so I'll offer a Python attempt. You would need to change from the Visual Basic parser to the Python parser and give something like this a try:

def FindLabel ( [PIPE_MATL], [PIPE_DIA] ):
  # assign pipe diameter string to S
  S = [PIPE_DIA]
  # trim the double-quote character from the end of the diam string/chg to float variable
  if (float(S[:-1]) > 2.0):
    return [PIPE_MATL]
  else:
    return ''

Be sure to keep the indentations intact if you cut-&-paste this. Whitespace/indentation is important/means 'run this block of code together' to Python.