topic Re: How to use Python Pre-Logic in Field Calculator in Python Questions

How to use Python Pre-Logic in Field Calculator

Anonymous User — Mon, 07 Jan 2013 16:17:31 GMT

I am trying to use if/then python pre-logic in field calculator to only change the value of a field when one or two other fields equal a predefined value. I can get it to work partially using the following code but it does not keep the original values for fields where "if=FALSE". I have tried using "pass" but it does not seem to work the way I need it to.

Pre-logic:
def myfunc(SYMBOL,ID,OPER_MAINT_LEVEL):
    if ID == "4648" and OPER_MAINT_LEVEL == "1 - BASIC CUSTODIAL CARE (CLOSED)":
        return 4
    if ID == "4654":
        return 4
    if ID == "4663C" and OPER_MAINT_LEVEL == "1 - BASIC CUSTODIAL CARE (CLOSED)":
        return 4
    else:
        SYMBOL
SYMBOL=
myfunc( !SYMBOL!, !ID!, !OPER_MAINT_LEVEL! )

Re: How to use Python Pre-Logic in Field Calculator

MathewCoyle — Sun, 12 Dec 2021 03:55:50 GMT

I think you want to do this.

def myfunc(SYMBOL, ID, OPER_MAINT_LEVEL):
    if ((ID == "4648" and OPER_MAINT_LEVEL == "1 - BASIC CUSTODIAL CARE (CLOSED)") or
            (ID == "4663C" and OPER_MAINT_LEVEL == "1 - BASIC CUSTODIAL CARE (CLOSED)")
            (ID == "4654")):
        return 4
    else:
        return SYMBOL

Re: How to use Python Pre-Logic in Field Calculator

Anonymous User — Sun, 12 Dec 2021 03:55:53 GMT

I think you want to do this.

def myfunc(SYMBOL, ID, OPER_MAINT_LEVEL):
    if ((ID == "4648" and OPER_MAINT_LEVEL == "1 - BASIC CUSTODIAL CARE (CLOSED)") or
            (ID == "4663C" and OPER_MAINT_LEVEL == "1 - BASIC CUSTODIAL CARE (CLOSED)")
            (ID == "4654")):
        return 4
    else:
        return SYMBOL

Thanks. I did not think to put it all into one query line. This seems to work except when ID and/or OPER_MAINT_LEVEL is null it does not return the value for SYMBOL. Is there a way still return the SYMBOL value when there are nulls in these fields? What about adding
elif ID== "NULL" or Oper =="NULL": return SYMBOL/

Re: How to use Python Pre-Logic in Field Calculator

MathewCoyle — Sun, 12 Dec 2021 03:55:56 GMT

Nulls are a little tricky. You could give something like this a try.

if not ID or not OPER_MAINT_LEVEL:
    return SYMBOL

Re: How to use Python Pre-Logic in Field Calculator

Anonymous User — Sun, 12 Dec 2021 03:55:58 GMT

Nulls are a little tricky. You could give something like this a try.
if not ID or not OPER_MAINT_LEVEL:
    return SYMBOL

Here is how I got it to work using str(!OPER_MAINT_LEVEL!):

def myfunc(SYMBOL,ID,OPER_MAINT_LEVEL):
    if not ID or not OPER_MAINT_LEVEL:
        return SYMBOL
    if ((ID == "4648" and OPER_MAINT_LEVEL == "1 - BASIC CUSTODIAL CARE (CLOSED)") or 
        (ID == "4654") or
        (ID == "4663C" and OPER_MAINT_LEVEL == "1 - BASIC CUSTODIAL CARE (CLOSED)")):
        return 4
    else:
        return SYMBOL

Expression:
SYMBOL =
myfunc(!SYMBOL!, !ID!, str(!OPER_MAINT_LEVEL!) )

Thanks for your help on this.