Chapter 1. Fundamentals of the Python Language for ArcGIS

Python supports many of the programming constructs found in other languages. In this chapter, we'll cover many of the basic language constructs found in Python. Initially, we'll cover how to create new Python scripts and edit existing scripts. From there, we'll delve into language features, such as adding comments to your code, creating and assigning data to variables, and built-in variable typing with Python, which makes coding with Python easy and compact.

Next, we'll look at the various built-in data types that Python offers, such as strings, numbers, lists, and dictionaries. Classes and objects are a fundamental concept in object-oriented programming and in the Python language. We'll introduce you to these complex data structures, which you'll use extensively when you write geoprocessing scripts with ArcGIS.

In addition to this, we'll cover statements, including decision support and looping structures to make decisions in your code, and/or looping through a code block multiple times along with the with statement, which is used extensively with the cursor objects from the ArcPy data access module that are used to insert, search, and update data. Finally, you'll learn how to access modules that provide additional functionality to the Python language. By the end of this chapter, you will have learned the following:

• How to create and edit new Python scripts in IDLE
• How to create and edit scripts in the ArcGIS Python window
• The language features of Python
• Comments and data variables
• Built-in data types (strings, numbers, lists, and dictionaries)
• Complex data structures
• Looping structures
• Additional Python functionalities