How to calculate a string with the value from the previous string

SlavaSemenov

Dear all, please tell me, what code should I type in the calculator ArcGIS for fill strings with the value from the previous strings (from different columns)

  

DavidPike

It's very messy, but this should work (you'll have to enter the first value manually after).  I'm also not sure how it will cope with the logical test on empty strings rather than Null (None type) but we can adjust, or possibly export to a table which sets Null values.

pre-logic script code block

true_false = False
value = ''
def my_function(field1, field2):
    global true_false
    global value
    if field1:
        true_false = True
        return value
        
    elif true_false:
        value = field2
        true_false = False

Field3 =

my_function( !Field1!, !Field2!)