Module 6: Working with Geometries

This week, I worked with shapefile geometries and extracting vertex data using Python scripting. I learned how to use the Search Cursor function on existing shapefile features. In orgder to do this, it was important to understand the structure of geometry objects, containing arrays of points. Features represent geographic objects as rows in the attribute table. Arrays organize the points that make up a feature’s geometry, and points define individual coordinates as vertices. I also used code to write vertex coordinates to a text file in an organized and readable way.

I chose to write ths script in IDLE . I started by importing arcpy, setting the workspace and overwrite environment, and defining the feature class (rivers.shp). Then I created a Search Cursor to access the Object ID, geometry, and name of each feature. I opened a text file for writing and used nested loops to iterate through each feature and its vertices, using the .getPart(0) method. For each vertex, I incremented a vertex ID and wrote a line to the text file with the feature ID, vertex ID, X and Y coordinates, and river name. Adding "\n" at the end of each line made the output readable.

Print statements were included inside the nested loops to display the feature OID, vertex ID, and the X and Y coordinates of each point as they were written to the text file. This helped me verify the script was processing each vertex correctly. Figure 1 is the result of my script.

Figure 1

This exercise improved my understanding of parsing complex geometries and exporting detailed spatial data using Python, which is valuable for automating GIS workflows.