Contents

• Overview
• Libraries in Python

Overview

Libraries in programming are collections of modules that provide sets of functions and classes to perform various tasks or operations. These modules are files containing prewritten code that developers can leverage to avoid "reinventing the wheel." For instance, the math library in Python offers mathematical functions and constants, while the datetime library provides classes and functions for manipulating dates and times. To use a library in Python, it must be imported to access the functions and other resources contained in the library.

A common question at this point is what is the difference between a function and a library? A function is a block of reusable code that performs a specific task within a program. In contrast, a library is a collection of related modules and functions external to a program. Think of a function as a single tool, like a screwdriver, and a library as a toolbox filled with various tools. While a function handles a specific operation, a library offers a suite of operations, often centered around a particular theme or domain. Both are integral to efficient programming, with functions providing the means to execute tasks and libraries offering a comprehensive set of tools and utilities for broader functionalities.

In programming, a library is a collection of prewritten, reusable, code that programmers can use to optimize tasks. These collections usually target specific categories of tasks, like mathematics, text analysis, mapping, etc. Programmers use libraries for several reasons, such as:

• Efficiency: Libraries save time. They contain prewritten code that you can incorporate into your projects, allowing you to focus on the unique aspects of your application.
• Simplicity: Using library functions, complex tasks can be accomplished with simple lines of code, making your code more readable and maintainable.
• Reliability: Libraries are often written and tested by experienced developers. This means that their functions are less likely to contain bugs than code you might write from scratch.
• Community and Support: Popular libraries come with a community of developers. This community can be a valuable resource for learning and troubleshooting.

Python, like many programming languages, has a rich ecosystem of libraries available for use. Some libraries are part of the Python language installation, called the Python Standard Library, and thousands of External Libraries available from various sources. The primary repository of external libraries is located online at pypi.org.

To use a library in Python, you use the import statement in your program along with the library's name of interest. For example, one of the libraries in the Standard Python Library is called math, which includes over 50 mathematical functions you can use in your programs. Here's a code example of using the math library:

import math
x = 9
y = 2
print(math.sqrt(x))
print(math.pow(x, y))
print(math.pow(x, (math.sqrt(x))))

Output:

3.0
81.0
729.0

Additional details about the Standard Python Library and External Libraries are provided on the next few pages.