Python expressions in field calculator

HelenCooper

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: 

Calculate Field examples—Help | ArcGIS Desktop 

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

perhaps

a <SPAN class="operator token">=</SPAN> <SPAN class="string token">'1234567890'</SPAN>

a<SPAN class="punctuation token">[</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="operator token">-</SPAN><SPAN class="number token">4</SPAN><SPAN class="punctuation token">]</SPAN>
<SPAN class="string token">'123456'</SPAN>

<SPAN class="comment token"># ---- if 'a' were the field name, you would use !a![:-4] in the field calculator‍‍‍‍‍‍‍‍‍‍‍‍</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>