topic Re: Calculate age in field calc using python parser in Geoprocessing Questions

Calculate age in field calc using python parser

JustinNettleton — Mon, 17 Dec 2012 15:48:48 GMT

I am looking to calculate an Age field from a DOB field using the python Parser in Desktop field calculator. Does anyone know the syntax I would need to use?

Thanks,

Re: Calculate age in field calc using python parser

AndrewChapkowski — Wed, 19 Dec 2012 15:43:52 GMT

Using the code box in field calculator, you can subtract two python datatime objects from each other.

For the code block use something like this:

def dateDiff(date):    from datetime import datetime    return int((datetime.now( ) - datetime.strptime(date,"%m/%d/%Y")).days/365.2425)

In the expression just enter in the name the following:

dateDiff( !DOB! )

Where field DOB is a date field.

Re: Calculate age in field calc using python parser

JustinNettleton — Fri, 21 Dec 2012 15:07:55 GMT

Thanks, works perfect.

Re: Calculate age in field calc using python parser

DanielO_Donnell — Tue, 12 Mar 2013 21:07:50 GMT

This works very well, unless there is a NULL value in a record. Naturally, one doesn't always have a DOB for each record.

Any ideas?

I Add Field "Age", then Calculate Field using the above python algorythm... however, I get an error when it hits NULL values.

ERROR 000539:
Error running expression datediff ( " " ) <type 'exceptions.ValueError'>: time data ' ' does not match format '%Y%m%d'
Failed to execute (Calculate Field: AGE)

Re: Calculate age in field calc using python parser

LucasDanzinger — Sat, 11 Dec 2021 19:47:19 GMT

If you are at 10.1, you can just test to see if a value is Null by checking to see if it equals None. This is highlighted in KB 40913.

You should be able to do something like:

def dateDiff(date):
   from datetime import datetime
   if date is None:
       pass
   else:
       return int((datetime.now( ) - datetime.strptime(date,"%m/%d/%Y")).days/365.2425)