Transitioning From Arcgis Gui To Efficient Python Scripting
The Problem with Clicking
The graphical user interface of ArcGIS provides an easy way to explore geospatial data and create simple maps. However, more complex geoprocessing workflows often require tedious sequences of tool dialog boxes and menu clicks. Each step must be manually adjusted and executed, making it time-consuming to perform multi-step analyses. Without scripting, it can also be difficult to replicate processes, share them with others, or customize them.
Tedious Workflows for Complex Geoprocessing Tasks
Operations like sophisticated proximity analysis, optimal routing, and predictive modeling can involve chains of multiple geoprocessing tools. Manually executing each step through a dialog box interface interrupts the workflow and hampers productivity. Clicking through the same sequences again and again becomes tedious for the GIS analyst.
Difficulty Replicating Analyses
GIS teams often need to perform the same or similar types of geoprocessing tasks on a regular basis. For example, a weekly analysis of new store locations based on population demographics and logistics. Without scripting, the multiple workflow steps must be redone from scratch each time. This makes replicating analytical processes time-consuming and prone to inconsistencies between runs.
Lack of Customization Options
While the tool dialogs provide basic parameters, there is little ability to customize and enhance the built-in tools. The GUI interface limits analysts who want to tailor processes and algorithms to their projects and data. Performing advanced modeling and analysis often requires going beyond what the GUI tools allow.
Python as an Efficient Alternative
Python scripting helps overcome the limitations of click-based GUIs for GIS processing tasks. Moving workflows from menus and buttons into Python code has many benefits:
Automating Workflows with Scripts
Complex chains of geoprocessing operations can be automated through Python scripting. This eliminates the need to manually run each step individually. Scripts allow analysts to define a sequence of tools just once, then execute them all at once with a single run.
Reusable and Customizable Code
Once scripts contain sequences of geoprocessing tasks, they become reusable templates for streamlining repetitive workflows. Scripts can also be customized to perform specialized analysis beyond what is available in the GUI tools.
Integrating Advanced Analysis and Modeling
Python opens up many more options for advanced GIS analysis using spatial statistics, machine learning algorithms, models, and more. These methods can be integrated directly into scripts along with standard geoprocessing tasks. Writing workflows in Python allows analysts to adopt more sophisticated approaches.
Setting Up Your Python GIS Environment
Getting started with Python GIS scripting requires setting up an appropriate Python environment and connecting it to your ArcGIS system or files. Here are the key steps for configuring your foundation:
Installing Python and GIS Packages
If not already available, install a Python distribution for your operating system like Anaconda. Make sure it includes key packages for geospatial analysis like NumPy, SciPy, Pandas, and others. The ArcGIS API for Python package should also be installed.
Connecting to ArcGIS Geodatabases
The scripts you write will need to access and use geodatabases containing your feature classes, rasters, and tables. Set up connections in Python to any GDBs you want to utilize by importing arcpy and using ArcPy data access modules.
Loading Datasets & Exploring Data
Use commands like arcpy.ListDatasets to programmatically view available geospatial datasets. Import them into Python scripts with arcpy.mapping modules and explore attribute data with Python data structures like DataFrames from Pandas.
Python Geoprocessing Fundamentals
Once connected to data, Python opens up many options for writing scripts to manipulate geospatial datasets. Master these core techniques for enhanced geoprocessing:
Reading and Writing Geospatial Data
Use File Geodatabase and Shapefile modules to read feature classes and rasters as Python objects you can analyze. Write results back out to new datasets with advanced data export options not available in the GUI.
Manipulating Geometries and Attributes
Access and iterate through features and attributes in datasets within scripts for specialized extract, transform, and load tasks. Update values, calculate new fields, and alter geometries using coordinate geometry modules.
Building Workflow Scripts
Construct sequences of data processing, analysis, and conversion tasks into reusable scripts that encapsulate entire workflows. Link I/O, iteration, conditional logic, and custom functions to replace clicking through chains of GUI tools.
Example Scripts
These examples demonstrate practical scripts to replicate common GUI geoprocessing workflows:
Selecting Features by Location
Perform spatial queries to select features based on proximity rules and relationships to other layers. Streamlines workflows relying on Select by Location tools.
Calculating Field Values
Populate attributes in a feature class by calculating values using mathematical and logical expressions. Applies consistent derivations across records.
Joining and Relating Tables
Link information between feature classes and external databases based on spatial and foreign key associations. Enhances data without modifications.
Creating Custom Tools and Applications
Scripting logic can also be encapsulated into reusable tools, models, and apps:
Building User-Friendly Interfaces
Wrap scripts into geoprocessing tools with customized parameters and user input dialogs. Creates friendly automation for common workflows.
Packaging Workflows as Tools and Apps
Combine interface and multiple backend scripts into distributable tools.Or build as web apps allowing cloud deployment with ArcGIS Online.
Distributing Solutions to End Users
Share workflow automation beyond the GIS group by publishing packaged tools, models, and apps externally or internally.
Further Resources for Learning
Many resources are available to level up your Python scripting skills:
Online Courses and Tutorials
Structured training content from Esri, LinkedIn Learning, Udemy, and others teach GIS focused Python programming.
ArcGIS API for Python Documentation
Comprehensive technical guidance covers the ArcPy library’s modules for manipulating geospatial data.
GIS Python Open Source Packages
Beyond ArcPy, packages like GeoPandas, Shapely, PyQGIS, and more extend capabilities.
The Path Forward
Transitioning from an ArcGIS Desktop centric workflow takes adjustment. Some tips:
Start Simple when Transitioning Workflows
Don’t try to boil the ocean early on. Pick small repetitive tasks to script out, then expand from there.
Leverage Existing Code Samples
Build knowledge faster by starting from provided code snippets rather than coding from scratch.
Join Python User Groups for Support
GIS focused Python forums and groups provide support channels to get guidance from peers.
