My python script calculates only the value of the immediate previous record

[OLANIYANOLAKUNLE]

My python script calculates only the value of the immediate previous record instead of calculating the values of all preceding records before that particular record. The example (the image) below is the undesired output;

While the image below here is what i want to achieve;

This is my python script i used;

import arcpy
from arcpy import da
CensusBldForm = "CensusBldForm"
Calculated_EA1=0
with arcpy.da.UpdateCursor(CensusBldForm, ["OBJECTID", "EstimatedPopulationinEA", "Calculated_EA"]) as cursor:
     for row in cursor:
          Calculated_EA2 = row[1]
          row[2] = (Calculated_EA1 + Calculated_EA2)
          Calculated_EA1 = Calculated_EA2
          cursor.updateRow(row)

Kindly assist me with the above please.

[WesMiller · Accepted solution]

Change this line

Calculated_EA1 = Calculated_EA2

To this

Calculated_EA1 += Calculated_EA2

[OLANIYANOLAKUNLE]

Thanks, it worked like magic

[WesMiller]

That's great! Please remember to mark your question as answered

[OLANIYANOLAKUNLE]

My edits don't get saved after running the script, because i have to start an edit session before running the script;

CensusBldForm = "CensusBldForm"

        Calculated_EA1=0

        with arcpy.da.UpdateCursor(CensusBldForm, ["OBJECTID", "EstimatedPopulationinEA", "Calculated_EA"]) as cursor:

            for row in cursor:

               Calculated_EA2 = row[1]

               row[2] = (Calculated_EA1 + Calculated_EA2)

               Calculated_EA1 += Calculated_EA2

               cursor.updateRow(row)

What do you think might be wrong or better still can i get it to run without starting an edit session i.e using a arcpy.UpdateCursor instead of arcpy.da.UpdateCursor? Thanks

[OLANIYANOLAKUNLE]

This is the error message i get when i want to save edits;

Kindly assist me please. Thanks in advance

[DanPatterson_Retired]

a wild guess that you aren't doing this on a file stored on your local machine but from sde or some other thing like that.  That error message has a history... there are some suggestion which you can search on geonet and narrow down the issue.  This is just one of several

https://community.esri.com/message/551258#comment-551258

[OLANIYANOLAKUNLE]

Thanks, i'm actually running my script against an SDE Geodatabase

[OLANIYANOLAKUNLE]

Thanks i changed from the default version to another version and i didn't get any error and my edits where retained as well.

[DanPatterson_Retired]

that is bad to hear from the threads... good luck