ArcGIS Desktop Advanced 10.2 - Calculate Field with codeblock?

Question

Hi,

In ArcGIS Advanced for Desktop 10.2, I am trying to calculate a field "ELEV_METER" in a shapefile with an expression and code-block as here:

expression = "getElev(double(!ELEV!))" codeblock = """def getElev(elev):      if elev <> 0:           return !ELEV!"""  arcpy.CalculateField_management(fc, "ELEV_METER", expression, "PYTHON_9.3",codeblock)

trying to apply ressources from ESRI:

http://resources.arcgis.com/en/help/main/10.1/index.html#//00170000004m000000

The calculate field should be done only if the field ELEV is not 0, then the if statment...

But is does not work! Any guess?

Cheers

VincentLaunstorfer · Accepted Answer

Thanks Daren,

In the codeblock, I now reference to the varaible elev in the return statment instead of the !ELEV! field directly. It is smarter.

However, what make the script crashing is the the CalculateField_management do not accept Null values for shapefile! Null values are possible only in Geodatabase, apparently.

It means, when elev = 0, CalculateField_management could not write Null in the "ELEV_METER" field...

Now it works as below:

expression =    "getElev(!ELEV!)"
       
codeblock = """def getElev(elev):
  if elev <> 0:
    return elev
  else:
    return -99"""
       
arcpy.CalculateField_management(fc, "ELEV_METER", expression, "PYTHON_9.3", codeblock)