Debugging GIS applications can be challenging, especially when you use third-party libraries that may have dependencies, compatibility issues, or bugs. In this article, you will learn some tips and tools to help you debug GIS applications with third-party libraries, such as GDAL, PyQGIS, and ArcPy.
An integrated development environment (IDE) is a software that helps you write, run, and debug code. Choosing the right IDE for your GIS project can make a big difference in your debugging experience. Some IDEs have features that are specific to GIS, such as spatial data viewers, map widgets, or geoprocessing tools. For example, QGIS has its own IDE called PyQGIS that allows you to access QGIS functions and modules from Python. Other popular IDEs for GIS include Visual Studio Code, PyCharm, and Spyder.
Truth be told that even the best programmers experience bugs which are a nightmare and having chosen the best IDE serves to differentiate how fast you can progress to finalize code development. The IDE choice can be dictated by a number of things, the development stack you are using, the experience you have in using the IDE as well as the programming language.
Logging and breakpoints are two common techniques to debug code by tracking the flow and state of your program. Logging is the process of recording messages or information in a file or console as your code executes. You can use logging to monitor the inputs and outputs of your functions, the values of your variables, or the errors and exceptions that occur. Breakpoints are points in your code where you can pause the execution and inspect the variables, expressions, or call stack. You can use breakpoints to identify where and why your code fails or behaves unexpectedly.
Sometimes, the problem is not in your code, but in the third-party library that you are using. To debug issues related to third-party libraries, you need to check the documentation and source code of the library. The documentation can provide you with information about the installation, usage, parameters, and outputs of the library functions and modules. The source code can show you how the library implements its logic and algorithms, and where it may have errors or limitations. You can also use the source code to modify or extend the library to suit your needs.
There are many tools and libraries that can help you debug GIS applications with third-party libraries. Some of these tools and libraries are general-purpose, while others are specific to GIS. For example, GDAL has a utility called gdalinfo that can display information about a spatial data file, such as its format, projection, extent, and bands. PyQGIS has a module called qgis.core that can perform various spatial operations, such as creating geometries, calculating distances, or clipping features. ArcPy has a function called arcpy.GetMessages that can return the messages generated by a geoprocessing tool.
The final step in debugging GIS applications with third-party libraries is to test and validate your results. Testing and validating your results can help you ensure that your code works as expected, and that your output is accurate and reliable. You can test and validate your results by using different data sets, comparing different methods, or applying quality checks. For example, you can use a test data set to run your code and compare the output with a known or expected result. You can also use different methods to perform the same task and see if they produce consistent results. You can also use quality checks, such as checking the projection, extent, or attributes of your output data.