Looping through all rows in single column and altering string values of each element in shapefile using ArcPy

Question

I have a shapefile with an attribute table that partially looks like this:

Row | Shape | Date
0 | Poly | 05-Sep-10 16:12:00
1 | Poly | 06-Sep-10 17:23:01

Is there a simple method that I can loop through the 'Date' column and add a 20 before the 10 in each cell? So that the output looks like this:

Row | Shape | Date
0 | Poly | 05-Sep-2010 16:12:00
1 | Poly | 06-Sep-2010 17:23:01

Date fields are text format.

I have been able to hand edit multiple rows, but let's say I have 10,000 rows, this would take a considerable amount of time.

Attempt using ArcPy in ArcMap:

import arcpy
path='C:/path/to/file.dbf'
field='Date' #name of the second column
twenty = '20'
with arcpy.da.UpdateCursor(path, field) as cursor:
 for row in cursor:
 new_row = row[0][:7] + twenty + row[0][7:]
 row = new_row
 print(row)
 cursor.updateRow(row)

Error I receive with this is:

TypeError: sequence of size must match the size of the row

Answer 1

Try changing:

row = new_row

to:

row = (new_row)

or:

row = [new_row]

I suspect your cursor needs either a list or tuple returned to it. That list or tuple will contain your single string.

Personally, I would do it, as @smiller commented, using something more like:

with arcpy.da.UpdateCursor(path, field) as cursor:
 for row in cursor:
 row[0] = "{}20{}".format(row[0][:7],row[0][7:])
 print(row)
 cursor.updateRow(row)

Answer 2

I think the pythonic (and universal) way of doing this is to convert those dates from string to datetime object and reformatting by using string directives. In your case, in a new field and using field calculator by Show Codeblock option:

Pre-logic script:

import datetime

new_field =

datetime.datetime.strptime(!Date!,'%d-%b-%y %H:%M:%S').strftime('%d-%b-%Y %H:%M:%S')