topic Re: Problem in Field Calculator in Geoprocessing Questions

Problem in Field Calculator

H_A_D_Padmasiri — Mon, 13 Jul 2015 10:09:39 GMT

Dear Sir!

I tried to customize a field value in polygon featureclass. For that I wrote a python function. Then using Field Calculator, I copy this function to Pre_Logic Script Code: and call the function. it gives me error.

Then I tried the same using Calculate Field tool in ArcToolbox. It works correctly.

Pl explain why I cannot run the above function using Field Calculator.

My function is given below:

def lblcal(a):

Dic1 = {'11':'PP', '13':'TOPOPP', '14':'FTP', '15':'VP', '16':'FVP', '17':'CP', '18':'FCP', '19':'FSP', '20':'FSPP', '21':'ISPP', '22':'FUP'}

if a[2:4] in Dic1.keys():

m = Dic1.get(a[2:4])

if (a[9] == 's') is True:

str1 = 'SUP' + str(int(a[10:15]))

else:

str1 = 'Inset' + str(int(a[10:15]))

if (a[15] == 's') is True:

str2 = 'Sheet' + str(int(a[16:20]))

str3 = m + ' ' + str(int(a[4:9])) + str1 + str2

return (str3)

I am working in ArcGIS 9.3

Thanks

Padmasiri

Re: Problem in Field Calculator

DanPatterson_Retired — Mon, 13 Jul 2015 10:41:44 GMT

you have to supply it with a field name as a substitute for 'a'

the function should go in the code block section then the call to the is made in the expression box like

lblcal([yourfield]) if using VB or lblcal(!yourfield!) if using the Python parser

Re: Problem in Field Calculator

XanderBakker — Sat, 11 Dec 2021 12:05:52 GMT

In addition to what Dan mentions, you should try and post the post using the instructions found here: Posting Code blocks in the new GeoNet

I copied the code and pasted it in an Python IDE and there were issues with the indentation. Apart from that you might be running into an error like "UnboundLocalError: local variable 'str3' referenced before assignment", since str3 only gets assigned in case a[15] is 's'.

def lblcal(a):
    Dic1 = {'11':'PP', '13':'TOPOPP', '14':'FTP', '15':'VP', '16':'FVP', '17':'CP', '18':'FCP', '19':'FSP', '20':'FSPP', '21':'ISPP', '22':'FUP'}
    if a[2:4] in Dic1:
        m = Dic1[a[2:4]]
        if a[9] == 's':
            str1 = 'SUP' + str(int(a[10:15]))
        else:
            str1 = 'Inset' + str(int(a[10:15]))
    if a[15] == 's':
        str2 = 'Sheet' + str(int(a[16:20]))
        str3 = m + ' ' + str(int(a[4:9])) + str1 + str2
    return (str3)

This code will probably still generate the error you encounter. What is the error you receive? Does it calculate for some records the values and breaks? Is it possible to provide some values of 'a' to check if it works?

BTW:

Dic1.keys() can be replace by Dic1
Dic1.get(a[2:4]) can be replaced by Dic1[a[2:4]]
if (a[9] == 's'): is True can be replaced by if a[9] == 's':
if (a[15] == 's') is True: can be replaced by if a[15] == 's':
Include at line before line 3 something like: str3 = "Error with: {0}".format(a) to avoid the code to break
There is no error checking (include try expect to catch errors)