Calculating geometry area in ArcGIS Desktop using ArcPy?

Question

I have a polygon shapefile and I want to write a Python script to add a field named "area" and calculate its geometry areas.

The script is like this:

arcpy.AddField_management("wrfd01_layer_intersect","area","LONG","","","","","NON_NULLABLE","NON_REQUIRED")
arcpy.CalculateField_management("wrfd01_layer_intersect","area","!shape.area@squaremeters!")

When I run it the field adds, and you can see the process of calculating the geometry area.

However, in the attribute table, there are no values in the field "area".

How to solve this problem?

Answer 1

Try this instead:

arcpy.AddField_management("wrfd01_layer_intersect","area","DOUBLE","#","#","#","#","NULLABLE","NON_REQUIRED","#")
arcpy.CalculateField_management("wrfd01_layer_intersect","area","!shape.area@squaremeters!","PYTHON_9.3","#")

I think you need to use a DOUBLE instead of LONG to get the desired area values. I suspect your "no values" are roundings of floating point numbers to an integer value of 0 - but I cannot be sure.

To get the above syntax I used Copy As Python Snippet from a successful run of each tool using its tool dialog.