Introducing Geographic Information Systems with ArcGIS: A Workbook Approach to Learning GIS, 3rd Edition

Create a Python Script from the Gold Model

Another way to automate geoprocessing activities is with scripts. These are programming instructions in languages that can be used to direct GIS processes. Writing scripts are beyond the scope of this book, but you should at least know of their existence and be able to execute one. You can use a model to make a Python script.

____ 18. Make a Python script of Gold_Model: Start ArcCatalog. Expand: ___ IGIS-Arc_YourInitials > Gold_Data > Toolbox.tbx > Gold_Model. Right click Gold_Model and choose Edit. Choose Model > Export > To Python Script. In the Save As window, navigate to

___ IGIS-Arc_YourInitials\Gold_Data

and name the file Gold_Model.py. (The extension “py” will probably be the only one available.) Click Save.

____ 19. Using a text processor (e.g., Notepad), open Gold_Model.py. As you scan the text, you can probably identify the processes that were used to solve the Getrich problem. Comments in the file (which are there for the human reading the code, not for execution by the computer) begin with a # character. Other lines are instructions to the Python interpreter. When Python executes this script, it will produce the same results as the model. There is one problem, however: If Python tries to write a file to a folder, and there is already a file by the same name in the folder, the program will bail out, giving you only an error message. Therefore, we need to slightly modify the program so that it will overwrite existing files ...