Module 05 - Debugging and Troubleshooting Python Scripts 

Summary:

I found this week’s assignment to have a lot of relevance in the “real world”.    The majority of the code you write will not work properly the first time you run it.   This is where your ability to debug and correct the course of the program is your most valuable asset.  

This week we learned several valuable skills towards that goal:

·         Benefits of using IDLE or PythonWin in different situations to improve debugging.

·         Identifying some of the most common errors and how to troubleshoot them.

·         The importance of indentation (and the difficulty in tracking down bugs related to indentation)

·         How to use the Alt-G command to jump to a specific line number to debug (very useful!!!)

·         How to use PDB to see behind the scenes.

·         How to use breakpoints and watches to better understand what is going on in your program.

·         How to understand the error messages that ArcGIS will display.

·         The use of some arcpy funtions like GetMessageCount() and GetMessages()

·         How to use Python to Programmatically buffer a point using the Geoprocessing tools.

I think you could attend an entire semester on this phase of the programming process and still not know all there is to know.   I have found that the ability to debug code is one of the most important skills you have as a programming professional.   It gets even more difficult when you have to debug code that someone else wrote.  

I picked up a couple of good books that might help the people in this class learn a bit more about ModelBuilder and Python.

They are :

Getting to Know ArcGIS ModelBuilder – by David W. Allen  ISBN-10: 1589482557

And

A Python Primer for ArcGIS by Nathan Jennings -  ISBN-10: 146627459X

In particular, I really like the David W. Allen Book.