Libraries in Python
Libraries are crucial parts of Python programming, helping to arrange code and expand the language’s capabilities. Frequently used interchangeably with packages or modules, they are code collections that facilitate the management, modification, and comprehension of large projects. Code can be arranged into modules in the same way that a book is arranged into chapters. Libraries make development easier and enable programmers to group functionality into reusable components by offering tested and dependable code that can be reused.
What are Libraries (Modules/Packages)?
In essence, a library, often known as a package, is a group of code structured frequently as modules. While chapters in a book organise portions, modules themselves can be viewed as files containing libraries in python code. Real-world applications can have hundreds or even millions of lines of code, making it hard to handle everything in a single file. For this reason, organisation is essential. Organising code into distinct groups, such as packages and modules, makes it much easier to manage. Library packages are frequently used for general purposes.
Why Use Libraries?
Libraries greatly increase the capability of Python’s core language. They simplify application development by offering pre-written code for frequently performed operations. You can utilise libraries in python to handle text, modify data, network, and interact with the operating system without writing code. This “divide and conquer” method simplifies difficult programming. Reusing community-created, tested, and debugged library code speeds development. Among the many application domains that libraries support are web frameworks, email clients, content management, and many more.
How to Use Libraries Importing
The code must be imported into your program in order to be used within a library (module or package). The code from the designated module is made available to your existing program via the import line.
There are different ways to import
- To import a module in its entirety the import statement followed by the module name imports a whole module in Python. This is the easiest and most usual import method. When you import module name, Python finds the module file, compiles it to byte code if needed, and executes all its commands.
- Bringing in particular names from a module (variables, classes, functions) the from module import name statement imports functions, classes, and variables from a module into your Python programs namespace.
- Since it can clog your program’s namespace, importing every name from a module is usually discouraged from import * from module name
Module name.function name() and specific name() are examples of dot notation that can be used to retrieve a module’s functions, classes, and other definitions once it has been imported.
Types of Libraries
There are two primary library categories in Python:
The Python Standard Library: The standard installation of Python includes a large collection of modules called the Python Standard Library. From working with files and networking to manipulating strings and numbers, it offers capabilities for a variety of activities. More than 200 built-in modules are included in the standard library.
External (Third-Party) Packages: External packages, often known as third-party packages, are community-developed libraries in python that are not included in the default Python installation. They cover a wide range of specialised topics, including graphical user interfaces, web programming, Data science, and machine learning. You may find hundreds of thousands of these modules online, frequently provided via the Python Package Index (PyPI). Installing these external libraries in python usually involves using a package management such as pip.
Learning About Libraries
Online documentation is usually available for libraries, particularly the official Python documentation for the standard library. A module’s documentation (typically derived from docstrings) and contents can be seen using Python’s built-in help() method. Learning how the code functions and possibly picking up new programming skills can be facilitated by looking at the.py files. To describe the function and use of code objects such as modules, functions, and classes, docstrings special multi-line comments are utilised.
Code Example: Using the math Library
The math module is a typical illustration of a standard library module. You can access mathematical functions with this module.
# Example of using a standard library module
# Import the entire math module
import math
# Use a function from the math module to calculate the square root
number = 25
square_root = math.sqrt(number)
print(f"The square root of {number} is {square_root}")
# Use another function from the math module
angle_degrees = 90
# Convert degrees to radians for trigonometric functions
angle_radians = math.radians(angle_degrees)
sine_value = math.sin(angle_radians)
print(f"The sine of {angle_degrees} degrees ({angle_radians:.2f} radians) is {sine_value}")
# Import a specific function from the math module
from math import pi
# Use the imported variable directly
print(f"The value of pi is approximately {pi}")
# You can still use other functions by prefixing with math.
radius = 5
area = pi * math.pow(radius, 2) # using math.pow and the imported pi
print(f"The area of a circle with radius {radius} is approximately {area:.2f}")Output:
The square root of 25 is 5.0
The sine of 90 degrees (1.57 radians) is 1.0
The value of pi is approximately 3.141592653589793
The area of a circle with radius 5 is approximately 78.54Explanation of the Example
Import math: The complete math module is imported by this line. After this line runs, you can use math to prefix any function or constant in the math module.
Math.sqrt(number): The math module in Python contains the sqrt() function, which calculates the square root of an integer. This function requires importing the math module with import math.
Math.radians: The standard Python math module includes math.radians(). It requires importing the math module using import math. Its main function is converting degrees to radians. This conversion is useful since several math module trigonometric functions, such as math.sin(), math.cos(), and math.tan(), require radians as input angles.
Math.sin: Python’s sin() method calculates angle sine. The math module in the standard library includes this function. Math.sin() requires importing the math module with import math.
From math import pi: This line imports just the particular math module constant pi. Once this is done, you can use pi without the math prefix.
pi * math.pow(radius, 2): The pow function obtained via the math. prefix (which is still available because we imported the entire module initially, but importing particular names is frequently done without importing the entire module first) and the directly imported pi are both used in this line.
This straightforward example demonstrates how importing a library (or module) helps you avoid writing complicated mathematical functions by providing you with pre-written code that accomplishes practical tasks. This is a fundamental tenet of Python programming library usage.