How to assign IDs to villages which may have duplicate names?

Question

I have more than 150 village points, each with a village name attribute village. The same village name may appear on multiple points.

I want to assign individual IDs for each village name, say vill_A = 1, vill_B = 2, and so on. I tried to calculate [village], but it didn't work.

Any suggestions?

Answer 1

I agree with @Brad Nesom that calculating a field based on FID or OBJECTID is the simplest way, although if for some reason you need a python approach in the field calculator, try this calculation on a new integer field:

rec=0   
def autoIncrement():   
 global rec 
 pStart = 1  
 pInterval = 1   
 if (rec == 0):     
  rec = pStart     
 else:  
  rec += pInterval   
 return rec

Add to the box below the code block:

autoIncrement()

Press OK

Answer 2

The best way to handle the unique values where there can be duplicates is to use a Python dictionary to link the Village name to the id number.

Here is an example Python field calculation code block:

villages = {}
id = 1
def GetID(village):
    global villages
    global id
    if not village in villages:
        villages[village] = id
        id += 1
    return villages[village]

Then simply call GetID(!VillageNameField!) for the expression.

This will create an empty Python dictionary called villages. Then, for each record in the Village Name Field it will remember if it has already assigned an id number to that village based on whether it already exists in the dictionary. If the village does not already exist in the dictionary it will assign it the next sequential id number. Finally, it returns the id number associated with the village from the dictionary whether it was already there or had to be added.

Answer 3

Probably the quickest way is,

1. create a new field for the values. i.e. [vill_id]
2. cacluate the oid (FID) into the vill_id.

Answer 4

If you are looking for any programming solution, you may think about creating a dictionary. IDictionary<string, List<int>> dictionary = new Dictionary<string, List<int>>();

Here,

• Key = Village_name
• Value = List of oid

Now you can assign values for all these oids or whatever you want.