Python to read text file to add new field

Question

So far I have written the following and both work:

arcpy.AddField_management("Wards", "test", "SHORT")

iFile =r'\file\Book1.txt'
f = open(iFile, 'r')

What I want to do is populate the new field 'test' with a field (value) from the iFile based on a match on two codes in the seperate file.

The text file has:

Code, Value

I think it might need updateCursor with a where statement ... or an if?

if (code in iFile == code in Wards):
    raise iFile(value) 

Answer 1

You can create a dictionary from the textfile and use in the UpdateCursor:

Textfile:

A Monkey
B Fish
C Cat
D Dog

Feature class attribute table:

Code:

import arcpy
feature_class=r"C:\TEST.gdb\polygons123"

#Create a dictionary for use in the updateCursor:
d = {}
with open(r"C:\Test\textfile.txt") as f:
    for line in f:
        (key, val) = line.split()
        d[(key)] = val

arcpy.AddField_management(in_table=feature_class, field_name='Newfield', field_type='TEXT', field_length=20)
with arcpy.da.UpdateCursor(feature_class,['IDField','NewField']) as cursor:
    for row in cursor:
        try:
            row[1]=d[row[0]] #'NewField' = Dictionary['IDField']
            cursor.updateRow(row)
        except:
            pass

Result: