topic Re: Python expressions in field calculator in Python Questions

Python expressions in field calculator

HelenCooper — Thu, 19 Sep 2019 10:30:19 GMT

Hi all,

I'm transitioning from ArcMap to ArcGIS Pro - no experience of Python but would like to learn.

I'm trying to run a very simple string function to remove four digits at the end of text field. In ArcMap VB Script I would do the following:

Left([FieldName],Len([FieldName])-4)

I can't see how to do the same in Python.

There seem to be relatively few examples here:

and the link to the build in functions of Python returns a 404 error.

Is there a good resource that sets out the functions and arguments for Python in ArcGIS? I have googled but can't find what I'm looking for!

Thanks in advance for any help,

Helen

DanPatterson_Retired — Sun, 12 Dec 2021 04:29:58 GMT

perhaps

a = '1234567890'

a[:-4]
'123456'

# ---- if 'a' were the field name, you would use !a![:-4] in the field calculator‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

DanPatterson_Retired — Thu, 19 Sep 2019 10:50:18 GMT

I find the python docs succinct and complete

HelenCooper — Thu, 19 Sep 2019 10:51:11 GMT

Thanks Dan,

That worked perfectly - any suggestions on good resources for learning?

Thanks,

Helen

HelenCooper — Thu, 19 Sep 2019 10:51:41 GMT

Perfect, I will take a look, very many thanks.