topic Re: KeyError: '#' When Calculating Geometry in Arcpy in Python Questions

KeyError: '#' When Calculating Geometry in Arcpy

JamesWilcox1970 — Thu, 25 Feb 2021 23:23:08 GMT

As part of a larger script, I have code that checks to see if a particular field exists. If not, it creates it and calculate its area. The script works just fine until it goes to calculate the area of the newly created field, where it gives me KeyError: '#'. Is this error because the field was just created? If so, how do I work around it?

I am running Python 3.6 with PyCharm.

Here is the code I am having issues with--"projArea" is the project area feature class.

# Test to see if there is an "Acres" field in the Project Area FC. projFields = arcpy.ListFields(projArea) # List of fields in project area fc x = False # Default condition is that the field doesn't exist for f in projFields: if f.name == "Acres": # If there is a field named "Acres" x = True if x is not True: # If none of the fields are named "Acres" arcpy.AddMessage("{} does not have an Acres field. Creating field.".format(projArea)) arcpy.AddField_management(projArea, 'Acres', 'DOUBLE') # Create the field arcpy.AddMessage("Calculating area.") arcpy.management.CalculateGeometryAttributes(projArea, 'Acres', area_unit="ACRES") # Calculate the area arcpy.AddMessage("Area calculated.")

Any help would be appreciated.

Re: KeyError: '#' When Calculating Geometry in Arcpy

DanPatterson — Thu, 25 Feb 2021 23:42:46 GMT

["Left", "EXTENT_MIN_X"]

in your case

[projArea, 'AREA']

Calculate Geometry Attributes (Data Management)—ArcGIS Pro | Documentation

a list is required for the first parameter, the field name and the property

Re: KeyError: '#' When Calculating Geometry in Arcpy

DavinWalker2 — Fri, 26 Feb 2021 05:28:57 GMT

Replace

arcpy.management.CalculateGeometryAttributes(projArea, 'Acres', area_unit="ACRES")

With arcpy.management.CalculateGeometryAttributes(projArea, [["Acres", "AREA"]], area_unit ="ACRES")

Re: KeyError: '#' When Calculating Geometry in Arcpy

JohannesLindner — Tue, 02 Mar 2021 06:58:30 GMT

What Dan and Davin said.

Plus, you can just do this:

#projFields = arcpy.ListFields(projArea) #x = False #for f in projFields: # if f.name == "Acres": # x = True projFieldNames = [f.name for f in arcpy.ListFields(projArea)] # extract field names x = "Acres" in projFieldNames # Test if field "Acres exists

Re: KeyError: '#' When Calculating Geometry in Arcpy

JamesWilcox1970 — Fri, 05 Mar 2021 20:13:32 GMT

That worked! I *knew* it was something that was staring me in the face. Thank you, all!

Re: KeyError: '#' When Calculating Geometry in Arcpy

ConradSchaefer__DOIT_ — Fri, 30 Jan 2026 15:56:49 GMT

Encountered this issue too. The trick ended up being that I had to pay attention to the Data Type for the geometry_type parameter in the function arcpy.CalculateGeometryAttributes(). Documentation says it is a Value Table type, which was new to me.

https://pro.arcgis.com/en/pro-app/3.4/tool-reference/data-management/calculate-geometry-attributes.htm

geometry_property parameter data type

Value Table documentation https://pro.arcgis.com/en/pro-app/3.4/arcpy/classes/valuetable.htm

The solution using the list of lists appears to be satisfying the Value Table format.

value_table = arcpy.ValueTable(2) # 2 is the number of columns I needed value_table.addRow(["field name 1", "data type 1"]) # 0 index value_table.addRow(["field name 2", "data type 2"]) # 1 index # NOTE: see https://pro.arcgis.com/en/pro-app/3.4/arcpy/geoprocessing_and_python/defining-parameter-data-types-in-a-python-toolbox.htm for options on data types arcpy.management.CalculateGeometryAttributes(in_features=feature_layer_name, geometry_property=value_table.getRow(0), coordinate_system=sr, coordinate_format="Same as input") # NOTE: sr is an arcpy.SpatialReference() object

If you call value_table.exportToString() on my example table above you get the following string format. Maybe the list of lists and the below quoted space separated and semi-colon delimited string also does the trick (?)

"'field name 1' 'data type 1';'field name 2' 'data type 2'"