Accumulating values of date field using Python parser of ArcGIS Field Calculator?

Question

I would like to modify the following accumulative/sequential python code sample in field calculator in a Date Time field. I think this is the correct code to use but let me know if not. The Date Time field is formatted like so: 30/01/2015 18:30:00. I need to add increments of 162 seconds to the time portion of the value for 24 records. The date will not change.

Here is the code sample copied from http://resources.arcgis.com/en/help/main/10.2/index.html#//00170000004s000000 and I've put my field name 'Date_Time) in

Expression:

accumulate(!Date_Time!)

Expression Type:

PYTHON_9.3

Code Block:

total = 0
def accumulate(increment):
 global total
 if total:
 total += increment
 else:
 total = increment
 return total

I know that I can change a single row's Date_Time value once by running this syntax in field calculator: DateAdd ("s", 162, [Date_Time] ) but I need to loop through the values in the Date_Time column starting with 30/01/2015 18:30:00 for the first row and adding 162 seconds to the new total each time.

• FelixIP: You can use simple expression, no code Dateserial(2015,01,30)+18.5/24+162* [FID]/24/60/60

Answer 1

The way I just did this assumes that you are using a file geodatabase features class, with an OBJECTID field that starts at 1.

I've called my date field DateField so change that for yours.

Parser: Python

Code Block:

def inc162secs(oid):
 startDataObj = datetime.datetime.strptime("30/01/2015 18:30:00", "%d/%m/%Y %H:%M:%S")
 return startDataObj + datetime.timedelta(seconds=( (oid - 1) * 162))

DateField =

inc162secs( !OBJECTID! )

The result was:

enter image description here

• GIS Adjunct in Training: Thank you PolyGeo!!! Amazingly fast and completely satisfactory reply - your answer was exactly what I was looking for! I just applied it and !BAM! perfect results.
• PolyGeo: By coincidence I wrote a similar example into one of my eLearning videos this morning so I had the answer at my fingertips.