Need help with Python Calculations!

Question

Can anyone please help me with a short program in Python scripting. I need a short program that will allow me to do a field calculation (Such as : population per square mile), and put the answer in a field (POPSQMILE) that was created in the editing session. Anything will help. Thanks!!

RyanForbes1 · Answer

The link I posted has all of the information you need to make the calculation happen via Python.
import arcpy

# path on the drive to the feature you're trying to manipulate.
inFeature = r"..."

# SQL expression you want to do.
expression = "[field1] + [field2]"

# The name of the output field.
outField = "field3"

# the tool.
arcpy.CalculateField_management(inFeature, outField, expression)

MichelleCouden1 · Answer

I know I can use the field calculator. I need a python program to do the same thing. Calculate two fields into one field. I was wondering if anyone knew how to write such a program. Please help!!!

RyanForbes1 · Answer

That's right - the only situation I can imagine where you would prefer Python over doing the field calculation is if you have many, many features where you need to perform this calculation and you want to automate it.  In that situation you might be interested in reading http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00170000004m000000 as this details how to use the field calculator in arcpy.