Finding difference between populations from 1990 to 2010 and writing info to new field using ArcPy? [closed]

Question

I am trying to write a script that finds difference but every time I use the information from instructor, I am getting an error, and getting nowhere...

table: field one is: Area_name, field two is 1990 POP, field 3 is pope 2000, and field four is pop 2010...

using ArcCatalog, I created a database located at C:/EsriPress/Script_4/US_County.gbd

broken script:

import arcpy
arcpy.env.workspace="C:/EsriPress/Scripting_4/US_County.gbd"
arcpy.env.overwriteOutput = True
fc = "US_County"# database
with arcpy.da.UpdateCursor(fc, ["Area_Name", "Resident_Population_1990", "Resident_Population_2010",
                                    "SHAPE@Resident_Population_2010", "SHAPE@Resident_Population_1990"]) as cursor:
    for row in cursor:
        Area_Name= row[0]
        x=row[1]
        y=row[3]
        row[4]=x
        row[5]=y
        cursor.updateRow(row)
del cursor

Can someone help?

Answer 1

It is a bit unclear what you want to do but you cant add new fields using the UpdateCursor, you need to use Add Field.

The shape tokens, like SHAPE@, or SHAPE@XY is for example when you need to modify geometries, or retrieve information about them. You should not need them for your problem.

I am assuming you want to add two new fields and populate with the differences of three existing fields:

import arcpy

arcpy.env.workspace=r"C:\EsriPress\Scripting_4\US_County.gbd"
arcpy.env.overwriteOutput = True
fc = "US_County"

fields_to_create = ["Diff_1990_2000", "Diff_2000_2010"]

for field in fields_to_create:
    arcpy.AddField_management(in_table=fc, field_name=field, field_type='DOUBLE')

input_fields = ["Pop_1990","Pop_2000","Pop_2010"] #Change to match the name of the existing fields

with arcpy.da.UpdateCursor(fc, input_fields+fields_to_create) as cursor:
    for row in cursor:
        row[3] = row[1]-row[0]
        row[4] = row[2]-row[1]
        cursor.updateRow(row)