How to travers fields of records without introducing them all in the function?

Question

In my previous question I wanted to reach a field in the field calculation; however, it was pretty easy to introduce a few more inputs for that function.

Now, I am facing a problem which needs around a hundred inputs. It might be a very naive question but I am wondering if there is a way to introduce an input to the function which is an object of the record type and then by a for loop I can traverse through the fields and sum them up.

My data includes the number of people for each age from 0 to 100 year-old and I want to calculate the number of people less than 30, above 30, less than 50 and above 50. So, having 50 inputs for the function and changing them for each new field is time-consuming. I think there is supposed to be a more efficient way.

Answer 1

Maybe I'm misunderstanding what you're looking for, but wouldn't a Select by Attribute work for this? Select From YourTable Where Age > 30, for example? You could run this, get the count, and update any fields accordingly. Or is that not what you want?

Answer 2

I haven't ever used the Field Calculator in that way and I'm not sure if what you ask is doable in that interface. You could use the CalculateField_management() tool in a python script which might give you more leeway in accessing the row because your beginning from outside the row and could then pass whatever arguments you want.

If I tried to do something like what your asking, I would use the Python Interpreter and use ListFields(), an UpdateCursor(), maybe some AddField()s to get the results I want. Here is an example. I've made the new fields in the code, but you can make them beforehand and just reference them if you like...

import arcpy
dataset = c:\mydataset.shp #Use your own dataset here
fieldlist = arcpy.ListFields(dataset,"","Integer")
arcpy.AddField_management(dataset,"YOUNG","LONG")
arcpy.AddField_management(dataset,"OLD","LONG")
arcpy.AddField_management(dataset,"NRLY_DEAD","LONG")

rows = arcpy.UpdateCursor()

for row in rows: # Loop through Records
  for field in fieldlist: # Loop through Fields
    if row.getValue(field) == 2:
      row.YOUNG += 1
    elif row.getValue(field) > 2:
      row.OLD += 1
    else:
      row.NRLY_DEAD += 1
  rows.updateRow(row)
del rows

I expect you'll still need to add logic to deal with the different fields that are encountered (expand on the if/else statements, depending on what field name is encountered), but you might find some ideas in there...